![principally obtained from the Silurian limestones, at Lake Huron; they
also occur in Ireland. Mr. Stokes, who first investigated their structure,
has arranged them in a distinct genus, with the name of Actinoceras
(radiated-horn).[413]
[413] See Geol. Trans, second series, vol. v. p. 708.
Slabs of reddish Devonian limestone, containing Orthoceratites,
may be seen in some of the pavements at Hampton Court, and in
Chelsea College, which when wet present excellent sections of the
enclosed shells.
Li g n . 156. Am m o n i t e s f r o m t h e Cr e ta c e o u s
Fo r m at i o n .
Fig.1.— Ammonites varians. Chalk-marl. Hamsey.
2.— Ammonites Dufrenoyi.
2a.—Shows the keel and septum of the same.
3.— Ammonites lautus. Galt. Folkstone.
3a.—Keel and septum of the same.](https://image.slidesharecdn.com/58561-250721231201-1cc283f7/85/Getting-Started-with-Ubuntu-12-10-1st-Edition-The-Ubuntu-Manual-Team-30-320.jpg)
![Li g n . 158. Am m o n i t e s
Ja s o n .
1
/2 n at . Oxford Clay,
Trowbridge, Wilts.
a.—Lateral processes of the
margins of the aperture
of similar siphuncles occur in the chalk, and have been mistaken for
tubular shells.
The outer lip, or margin of the
aperture, is occasionally found entire. In
some species there is a dorsal process, as
in a very common Chalk Ammonite (A.
varians, Lign. 156, fig. 1), which extends
far beyond the margin; in other species,
from the Oxford Clay, there are long,
narrow, lateral appendages, (Lign. 158).
In the collection of S. P. Pratt, Esq., there
is a small Ammonite, from the Inferior
Oolite of Normandy, in which these
processes meet over the aperture, leaving
only a circular aperture towards the back
of the shell (where the siphuncle of the
animal would be situated) and a narrow
fissure on the side next the involute spire.
The specimen is unique, and can scarcely be regarded as a normal
form.[414] (Mr. Woodward.)
[414] M. Steenstrup has described a species of Purpura, which
at the close of its life shuts up the aperture of its shell, with the
exception of the respiratory siphon.—Mr. Woodward.
From the small size of the cells of the Ammonites, particularly in
those species which are of a depressed or flattened form, it was long
doubted whether the outer chamber could have been sufficiently
capacious to contain the body of the animal; and it was supposed that
these shells were internal, like the recent Spirula, or Crosier. But Dr.
Buckland has clearly demonstrated, that the outer cell of the
Ammonite, if restricted in breadth, is sufficiently ample in length to
have contained the soft parts of a Cephalopod, equal in magnitude to
the largest known specimens, its proportion to the chambered part
being as considerable as in the Nautilus. The outer chamber often
occupies more than half, and in some instances the entire
circumference of the outer whorl (see Bd. pl. xxxvi.).](https://image.slidesharecdn.com/58561-250721231201-1cc283f7/85/Getting-Started-with-Ubuntu-12-10-1st-Edition-The-Ubuntu-Manual-Team-33-320.jpg)
![In certain argillaceous deposits, as the Galt, and the clays of the
Lias, Ammonites with the shell preserved are abundant; generally the
outer opaque layer is wanting, or adheres to the matrix when a
specimen is removed, leaving only the internal nacreous, or pearly
coat. Folkstone, on the coast of Kent, is celebrated for examples of this
kind, which may easily be collected from the Galt, which forms the
base of the cliffs, at Eastware Bay. Watchett, in Somersetshire, is
equally rich in the pearly Ammonites of the Lias; entire layers of these
beautiful organic remains occur in the limestones and in the shale
exposed at low water.[415]
[415] A splendid group of these Ammonites may be seen in the
Gallery of Fossils at the British Museum.
The shell of the Ammonite is generally thinner and more delicate
than that of the Nautilus. However thin these shells may be, they are
possessed of great strength of structure. Not only is the shell one
continuous arch, but it is moreover provided with transverse arches or
corrugated ribs, which, like the flutings on metal pencil-cases, and
corrugated sheet-iron, greatly strengthen the thin material. These ribs
are further subdivided, so as to multiply supports as the convexity of
the shell enlarges, in a manner somewhat similar to the groin-work of
vaulted roofs. The spines, tubercles, and bosses, which often arise
from the ribs, are so many additions to the strength of the latter. The
sides of the shell are also supported by the transverse plates forming
the septa, or divisions of the chambers, and, as these plates are very
sinuous where they meet the sides of the shell, they distribute their
support over a considerable portion of the surface.[416] These
complicated edges of the septa form the delicate and intricate lines of
foliation (sutures) seen on the casts of Ammonites (Lign. 156, fig. 2),
Baculites (Lign. 161, fig. 3), Hamites, &c. In some species the shell is
thick and dense, as in the Ammonites of the Kimmeridge Clay near
Aylesbury, in which one species (Ammonites biplex, Min. Conch. pl.
ccxciii.) in particular abounds, and is very generally invested with the
shell, as perfect as if recent. The same Ammonite occurs in the
Portland limestone above, in the state of casts, without any vestige of
the shell. In some strata the shell is replaced by calcareous spar; in](https://image.slidesharecdn.com/58561-250721231201-1cc283f7/85/Getting-Started-with-Ubuntu-12-10-1st-Edition-The-Ubuntu-Manual-Team-34-320.jpg)
![others by silex or flint.[417] In the pyritous clays and shales of the Lias,
the shell and all its delicate internal mechanism are coated with or
replaced by brilliant sulphuret of iron, forming the most exquisite
natural electrotype imaginable. Polished vertical sections of these
fossils often exhibit the inner cells filled with transparent white
calcareous spar; sometimes with groups of crystals of sulphate of lime.
The Ammonites of the Galt, and of the Kimmeridge Clay, are also
frequently imbued with the same mineral.
[416] See Bd. i. p. 339, &c.
[417] See an admirable figure of a chalcedonic specimen,
exhibiting the foliated septa of an Ammonite, Bd. pl. xli.
There are about two hundred identified species of Ammonite in the
British strata, ranging through all the secondary formations; they have
not been found in the Tertiary deposits. They vary in size from half an
inch to four feet in diameter.[418]
[418] I have seen imprints of the large Chalk Ammonite, A.
peramplus (Min. Conch. pl. ccclvii.), on the shore off Rottingdean,
and Beachy Head, which indicated even larger proportions.
Certain species are restricted to particular formations, and are
therefore oftentimes of essential aid in determining the relations of a
deposit; for example, the Galt contains several species not found in the
upper division of the Chalk; and in the Chalk-maid are species that
have not been discovered in other strata. Certain Ammonites of the
Lias are peculiar to that formation (as A. Walcottii, Lign. 127, fig. 7, p.
397; and A. communis, Lign. 157). Ammonites of species allied to
those of our Middle and Lower Oolites have been discovered in strata
in the Himalaya mountains, several thousand feet above the level of
the sea.](https://image.slidesharecdn.com/58561-250721231201-1cc283f7/85/Getting-Started-with-Ubuntu-12-10-1st-Edition-The-Ubuntu-Manual-Team-35-320.jpg)
![restricted to some of the older sedimentary strata; for although there
are sixty British species, none of them have been observed above the
Carboniferous system.[419]
[419] G. Henslowi, G. striatus, and G. sphæricus, are figured in
Bd. pl. xl.
In Ceratites the sutures are more simple than in the Ammonite,
being lobed rather than foliated; and the alternate lobes have their
edge crenulated or finely toothed. (C. nodosus, Bd. pl. xl.) This genus
is found in the Muschelkalk and the Keuper formations of Europe and
Asia.
Our limits will not permit us to extend this notice of the very
numerous family of Ammonitidæ,[420] except to offer a few
illustrations of some of the modifications in form to which we have
already alluded, and which will assist the student in discriminating
these fossil remains.
[420] For further information, Dr. Buckland’s Treatise, and the
respective articles in the Penny Cyclopædia, may be referred to. Mr.
Woodward’s Manual should be consulted for the classification of the
family, and M. D’Orbigny’s Paléontologie Française for the illustration
of species.
Crioceras (coiled-horn), Lign. 160, fig. 2.—This shell differs from the
Ammonites in the turns of the spire being distant from each other. The
siphuncle is continuous, and the septa are regularly divided into six
lobes. I have found specimens of this genus in the Chalk-marl at
Hamsey, and in the White Chalk, near Lewes (Foss. South D. tab. xxiii.
fig. 9).](https://image.slidesharecdn.com/58561-250721231201-1cc283f7/85/Getting-Started-with-Ubuntu-12-10-1st-Edition-The-Ubuntu-Manual-Team-37-320.jpg)
![SCAPHITE
In my early researches in the Chalk-marl of Hamsey, I discovered
numerous solid, oval, and cylindrical pipes of marl, with scarcely any
vestige of organic structure, whose origin it was impossible to
determine. At length I found the specimen, Lign. 161, fig. 2, which
showed the perfect aperture of a chambered shell; and afterwards I
found portions which displayed the foliated septa. (Foss. South D. tab.
xxiii. figs. 5, 6, 7.) The Baculite, when perfect, is elongated to a point;
the septa are very numerous and foliated; the siphuncle is situated on
the margin. I have a splendid specimen from the Chalk of France,
(collected by M. Alex. Brongniart,) which is composed of distinct casts
of the cells, held together by the deep inflections of their margins, in
the same manner as are the sparry casts of Ammonites, previously
described.[421]
[421] See Bd. pl. xliv, fig. 5.
The Galt, near Folkstone, abounds in fossils of the above genera,
principally of Hamites; and the nacreous substance of the shells is very
often preserved. From the Chalk-marl near Dover, Southbourn,
Ringmer, and Southerham, near Lewes, and from Clayton, near
Hurstpierpoint, in Sussex, I have obtained examples of several species.
Scaphites (boat-like). Lign. 162.—This name was given by Mr.
Parkinson (Org. Rem. vol. iii. pl. x. See Pict. Atlas) to some small
chambered shells from the Chalk and Shanklin Sand, of a boat-like
form, with the inner whorls coiled up in a spire, and half hidden by the
outer chamber, which becomes contracted and recurved on itself, is
destitute of septa, and terminates in an oval or transverse mouth. The
siphuncle is dorsal. An Ancyloceras closely coiled would be a Scaphite.
Hamsey marl-pit yielded to my early researches the first Scaphites
discovered in the British strata, together with Turrilites, and other
cephalopodous shells, previously unknown in England.[422] The
Scaphite is of an elliptical form, the spire and the mouth approaching
close to each other; the spire occupies about one-half of the shell.
Except the thick outer lip or margin of the aperture, which is almost
constantly found changed into pyrites, it is rarely that any vestige of
the shell remains. The same mineral constitutes casts of the spiral](https://image.slidesharecdn.com/58561-250721231201-1cc283f7/85/Getting-Started-with-Ubuntu-12-10-1st-Edition-The-Ubuntu-Manual-Team-41-320.jpg)
![part; and these, when separated from the other portion, might be
taken for Ammonites; see fig. 2. There are two varieties at Hamsey;
one, with the surface covered by fine transverse striæ, which arise
singly from the inner margins, and bifurcate on the dorsal part; fig. 1.
The other is also striated, but has a row of prominent ribs on the inner
half of the broad central portion of the shell; fig. 4. Scaphites occur in
the Upper Green Sand of Dorsetshire, and in the Chalk-marl in several
places in England; and at Rouen, in France; and a large species, S.
Cuvieri, has been found in New Jersey.
[422] Sow. Min. Conch, vol, i. p. 53.
Li g n . 162. Sc a p h i t e s . Chalk-marl.
Hamsey.
Fig.1 and 4.—Scaphites æqualis. (Parkinson.)
2.—Cast in pyrites of the spiral part of a Scaphite.
2a.—Front view of the same specimen.
3.—Front view of Scaphites æqualis.](https://image.slidesharecdn.com/58561-250721231201-1cc283f7/85/Getting-Started-with-Ubuntu-12-10-1st-Edition-The-Ubuntu-Manual-Team-42-320.jpg)
![TURRILITE
Li g n . 163. Tu r r i l i t e s . Chalk-marl.
Fig.1.—Turrilites catenatus. (M. D’Orbigny.) France.
a.—One of the septa.
2.—Turrilites costatus. Hamsey.
Turrilites. Lign. 163.—Shell spiral, more or less conical,
coiled obliquely round an axis, and turriculated. Spire sinistral, whorls
contiguous, apparent, with a perforated umbilicus. Edges of septa very
sinuous. Siphuncle continuous, situated either on the external
convexity, or near the suture at the base of the wreath.
The discovery of three species of these elegant shells rewarded my
researches in the little marl-pit at Hamsey, already noticed, and were
the first examples of the genus found in England.[423] Like the
Ammonites, Scaphites, Hamites, &c. with which they are associated,
the Turrilites of our Chalk-marl seldom possess any traces of their
shells. The specimens are solid and tolerably sharp casts, with](https://image.slidesharecdn.com/58561-250721231201-1cc283f7/85/Getting-Started-with-Ubuntu-12-10-1st-Edition-The-Ubuntu-Manual-Team-43-320.jpg)
![occasional indications of the septa, and more rarely of the siphunculus.
They vary in size from two or three inches to two feet in length; and
are frequently more or less elliptical, from compression. The three
species which generally occur in the Sussex and Kentish chalk, are T.
costatus, Lign. 163, fig. 2; T. tuberculatus (Foss. South D. pl. xxiv. fig.
7), characterised by its four rows of tubercles; and T. undulatus (Foss.
South D. pl. xxiv. fig. 8), the wreaths of which are ornamented with
plain, slightly undulated, transverse ribs. These are all reversed, or
sinistral shells; that is, the spire is twisted to the left, the aperture
being on the right hand of the observer when the shell is placed on its
apex, as in fig. 1. Several other species of Turrilites occur in the Chalk
of France,[424] one of which, T. catenatus, is represented Lign. 163,
fig. 1.
[423] Sow. Min. Conch, tab. xxxvi.
[424] See M. D’Orbigny’s Paléontologie Française.
Some of the Turrilites attain a considerable magnitude. The largest
found in England is a specimen of T. tuberculatus (Min. Conch. tab.
lxxiv.), from Middleham, in the parish of Ringmer, near Lewes; when
perfect, it must have been full two feet in length: it consists of six
wreaths, the siphuncle, in the state of pyrites, appearing in three or
four; portions of the nacreous internal layer of the shell remain.[425] In
some specimens in my possession, the form of the aperture, and the
termination of the columella, are distinctly shown; as in the fine
example the last whorl of which is represented in Lign. 164.
[425] This specimen is now in the British Museum.](https://image.slidesharecdn.com/58561-250721231201-1cc283f7/85/Getting-Started-with-Ubuntu-12-10-1st-Edition-The-Ubuntu-Manual-Team-44-320.jpg)
![APTYCHU
Li g n . 164. Tu r r i l i t e s t u b e r c u l at u s , (Bosc.) nat.
Chalk-marl, Lewes.
Showing the form of the aperture, and the spinous
tubercles. The specimen is a cast in indurated
chalk-marl; the last wreath only is figured.
Fig.1.
—
Posterior view, exhibiting the expanded outer lip, and
the obtuse termination of the columella.
2.
—
Front view, showing the form of the aperture.
a.—Two tubercles, bearing spines.
The Chalk-marl of Lewes, of the Sussex coast, and of the cliffs near
Dover, and the Upper Green Sand of Dorsetshire, have yielded the
principal British specimens of this genus. Several species occur in the
lower cretaceous strata, at St. Catherine’s Mount, near Rouen,
associated, as in England, with Scaphites, Hamites, and other allied
genera.[426]
[426] See Fossils of the South. Downs for figures of many
species of the Cephalopoda of the Sussex Chalk.
Aptychus, Meyer. (Trigonellites, Parkinson.) Lign. 165.—
Associated with the remains of Ammonites in several localities, are
found flattened triangular bodies, from less than an inch to an inch
and a half in diameter, the nature of which is still somewhat
problematical. A good figure is given by Mr. Parkinson of one species
(Org. Rem. vol. iii. pl. xiii. figs. 9, 10, 12. See Pict. Atlas), with the](https://image.slidesharecdn.com/58561-250721231201-1cc283f7/85/Getting-Started-with-Ubuntu-12-10-1st-Edition-The-Ubuntu-Manual-Team-45-320.jpg)
![General fossil
in the Tertiary
Formations
Sepiadæ
Sepia, Spirulirostra, Beloptera,
Belemnosis.
Nautilidæ Nautilus and Aturia
Cretaceous
Deposits
Belemnitidæ
Belemnites, Belemnitella, and
Conoteuthis.
Nautilidæ Nautilus.
Ammonitidæ
Ammonites, Crioceras, Scaphites,
Ancyloceras, Toxoceras, Hamites.
Ptychoceras, Helicoceras, Turrilites,
Baculites.
Oolite and
Lias
Sepiadæ Sepia.
Teuthidæ
Teudopsis, Beloteuthis, Geoteuthis,
Leptoteuthis, Ommastrephes.
Belemnitidæ
Belemnites. Acanthoteuthis, and
Belemnoteuthis.
Nautilidæ Nautilus.
Ammonitidæ Ammonites, Ancyloceras.
Trias
Nautilidæ Nautilus.
Ammonitidæ
[427] Ammonites, Goniatites, and Ceratites.
Carboniferous
System
Nautilidæ
Nautilus, Gyroceras, Cyrtoceras,
Gomphoceras, and Orthoceras,
Actinoceras, &c.
Ammonitidæ Goniatites.
Devonian
System
Nautilidæ
Nautilus, Clymenia, Cyrtoceras,
Phragmoceras, Gomphoceras,
Orthoceras, Actinoceras, &c.
Ammonitidæ Goniatites.
Upper and
Lower
Silurian
Systems
Nautilidæ
Nautilus, Lituites, Gyroceras,
Cyrtoceras, Phragmoceras,
Gomphoceras, Oncoceras, Ascoceras,
Orthoceras, Actinoceras, &c.
[427] The Ammonitidæ are from the St. Cassian beds only.](https://image.slidesharecdn.com/58561-250721231201-1cc283f7/85/Getting-Started-with-Ubuntu-12-10-1st-Edition-The-Ubuntu-Manual-Team-48-320.jpg)
![With regard to the zoological affinities between the living and
extinct species of testaceous Cephalopoda, Dr. Buckland remarks, "that
they are all connected by one plan of organization; each forming a link
in the common chain which unites the existing species with those that
prevailed among the earliest conditions of life upon our globe; and all
attesting the identity of the design that has effected so many similar
ends, through such a variety of instruments, the principle of whose
construction is, in every species, fundamentally the same.
"Throughout the various living and extinct genera of these beings,
the use of the air-chambers and siphuncle of their shells, to adjust the
specific gravity of the animals in rising and sinking, appears to have
been identical. The addition of a new transverse plate within the coiled
shell added a new air-chamber, larger than the preceding one, to
counterbalance the increase of weight that attended the growth of the
shell and body of these animals." (Bd. p. 380.)
The occurrence of the Nautilus, and its congeners, among the
earliest traces of the animal kingdom, and their continuance
throughout the immense periods during which the family of
Ammonitidæ was created, flourished, and became extinct, and the
existence of species of the same genus at the present time, are facts
too remarkable to have escaped the notice even of those who are not
professed cultivators of geological science; and I am induced to quote
the following beautiful lines, by Mrs. Howitt, to impress this interesting
phenomenon more strongly on the mind of the youthful reader.[428]
[428] The poetess has, however, not been literally accurate
regarding the Nautilus and its habits, nor as to the formation of
stratified rocks, but has given a romantic rather than a scientifically
correct view of this interesting Cephalopod, and of the
disappearance of its congener. The young reader must, therefore,
remember that the Nautilus sometimes floats, but never sails; and
that the whole race of Ammonites died out in course of time, and
were not annihilated by convulsive movements of earth and sea.
"TO THE NAUTILUS.
"Thou didst laugh at sun and breeze,](https://image.slidesharecdn.com/58561-250721231201-1cc283f7/85/Getting-Started-with-Ubuntu-12-10-1st-Edition-The-Ubuntu-Manual-Team-49-320.jpg)
![is A. biplex (Sow. Min. Conch.), which varies from three inches to one
foot in diameter; the surface is covered by very strong ribs that
encircle the whorls. The shell is thick, and composed of several
laminæ.[429]
[429] According to the observations of my son, the outer layers,
when highly magnified, present an appearance of opaque areolæ,
with irregular radiating fibres; the inner laminæ are covered with
minute pores, apparently the orifices of tubuli, some of which are
arranged singly in crescents, and others are confluent, like short
strands of beads. I mention the fact to direct attention to the
microscopic examination of the structure of these splendid fossils.
The sparry casts of the separate cells of Ammonites which occur in
some of the calcareous beds of the Oolite, will not fail to be observed
by the collector. It is convenient to preserve such specimens either on
a tray or board, in which a groove is made for their reception, or in a
mould of gutta percha.
In collecting Belemnitidæ, the caution already given, of examining
the surrounding clay or marl, must not be disregarded; the student
should remember, that traces of the soft parts of the animals, even of
mere impressions of the body and head, with the tentacula and their
acetabula, or little horny rings and hooks, are more important than the
most splendid examples of the spathose durable osselet. The guards
should be selected with especial reference to their containing the
phragmocone (see Lign. 141, fig. 2), or chambered conical shell, in the
alveolus or cavity of the upper and larger end. An apparently worthless
fragment of a Belemnite will often be found to possess this part of the
structure, as in the example figured, which, until fractured
longitudinally, had been thrown by among useless duplicates. The
search for the remains of the fossil naked Cephalopoda, as the
Teuthidæ and Sepiadæ, and their ink-bags, must be made in a like
cautious manner. In the Lias marls, the ink-bag and its duct is often
found partially covered by a pellicle of nacre, without any trace of the
other parts of the animal. A reference to Dr. Buckland’s plates (Bd. pl.
xxviii. xxix) will familiarize the student with the appearance of these
fossil remains.](https://image.slidesharecdn.com/58561-250721231201-1cc283f7/85/Getting-Started-with-Ubuntu-12-10-1st-Edition-The-Ubuntu-Manual-Team-52-320.jpg)
Getting Started with Ubuntu 12 10 1st Edition The Ubuntu Manual Team
- 1. Getting Started with Ubuntu 12 10 1st Edition The Ubuntu Manual Team - PDF Download (2025) https://ebookultra.com/download/getting-started-with- ubuntu-12-10-1st-edition-the-ubuntu-manual-team/ Visit ebookultra.com today to download the complete set of ebooks or textbooks
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- 5. Getting Started with Ubuntu 12 10 1st Edition The Ubuntu Manual Team Digital Instant Download Author(s): The Ubuntu Manual Team ISBN(s): 9781481265126, 1481265121 Edition: 1 File Details: PDF, 8.79 MB Year: 2013 Language: english
- 8. Copyright © – by e Ubuntu Manual Team. Some rights reserved. cba is work is licensed under the Creative Commons Aribution–Share Alike . License. To view a copy of this license, see Appendix A, visit http://creativecommons.org/licenses/by-sa/./, or send a leer to Creative Commons, Second Street, Suite , San Francisco, California, , USA. Geing Started with Ubuntu . can be downloaded for free from http:// ubuntu-manual.org/ or purchased from http://ubuntu-manual.org/buy/ gswu/en_US. A printed copy of this book can be ordered for the price of printing and delivery. We permit and even encourage you to distribute a copy of this book to colleagues, friends, family, and anyone else who might be interested. http://ubuntu-manual.org Revision number: Revision date: -- :: -
- 10. Contents Prologue Welcome Ubuntu Philosophy A brief history of Ubuntu Is Ubuntu right for you? Contact details About the team Conventions used in this book Installation Geing Ubuntu Trying out Ubuntu Installing Ubuntu—Geing started Finishing Installation Ubuntu installer for Windows e Ubuntu Desktop Understanding the Ubuntu desktop Unity Using the Launcher e Dash Workspaces Managing windows Browsing files on your computer Nautilus file manager Searching for files and folders on your computer Customizing your desktop Accessibility Session options Geing help Working with Ubuntu All the applications you need Geing online Browsing the web Reading and composing email Using instant messaging Microblogging Viewing and editing photos Watching videos and movies Listening to audio and music Burning CDs and DVDs Working with documents, spreadsheets, and presentations Ubuntu One Hardware Using your devices Hardware identification
- 11. . Displays Connecting and using your printer Sound Using a webcam Scanning text and images Other devices Soware Management Soware management in Ubuntu Using the Ubuntu Soware Center Managing additional soware Manual soware installation Updates and upgrades Advanced Topics Ubuntu for advanced users Introduction to the terminal Ubuntu file system structure Securing Ubuntu Why Ubuntu is safe Basic security concepts User accounts System updates Firewall Encryption Troubleshooting Resolving problems Troubleshooting guide Geing more help Learning More What else can I do with Ubuntu? Open source soware Distribution families Choosing amongst Ubuntu and its derivatives Finding additional help and support e Ubuntu community Contributing A License Creative Commons Aribution–ShareAlike . Legal Code Creative Commons Notice Glossary Credits Index
- 12. Prologue Welcome Welcome to Geing Started with Ubuntu, an introductory guide wrien to help new users get started with Ubuntu. Our goal is to cover the basics of Ubuntu (such as installation and work- ing with the desktop) as well as hardware and soware management, work- ing with the command line, and security. We designed this guide to be simple to follow, with step-by-step instructions and plenty of screenshots, allowing you to discover the potential of your new Ubuntu system. Ubuntu . is considered a regular release and is supported by Canon- ical with patches and upgrades for eighteen months. Ubuntu . is the most recent and has support for years. Whenever a new version of Ubuntu is released, we will incorporate updates and changes into our guide, and make a new version available at http://www.ubuntu-manual.org. Geing Started with Ubuntu . is not intended to be a comprehensive Ubuntu instruction manual. It is more like a quick-start guide that will get you doing the things you need to do with your computer quickly and easily, without geing bogged down with technical details. As with prior versions, Ubuntu . incorporates many new features, including a new kernel supporting newer graphics cards, updates to the Update Manager, and full-disk encryption, to name just a few. For more detailed information on any aspect of the Ubuntu desktop, see the “Ubuntu Desktop Guide,” which can be obtained in any of the following ways: ‣ in the Dash, type help. ‣ in the desktop menu bar, click Help ‣ Ubuntu Help. ‣ go to https://help.ubuntu.com, Ubuntu . ‣ Ubuntu Desktop Help. ere are also many excellent resources available on the Internet. For example, on https://help.ubuntu.com you will find documentation on in- stalling and using Ubuntu. At the Ubuntu Forums (http://ubuntuforums.org) and Ask Ubuntu (http://askubuntu.com), you will find answers to many Ubuntu-related questions. You can find more information about Ubuntu’s online and system documentation in Chapter 8: Learning More. If something isn’t covered in this manual, chances are you will find the information you are looking for in one of those locations. We will try our best to include links to more detailed help wherever we can. Ubuntu Philosophy e term “Ubuntu” is a traditional African concept originating from the Bantu languages of southern Africa. It can be described as a way of con- People sometimes wonder how to pronounce Ubuntu. Each u is pronounced the same as in the word put except for the last u which is pronounced the same as in the word due. necting with others—living in a global community where your actions affect all of humanity. Ubuntu is more than just an operating system: it is a community of people coming together voluntarily to collaborate on an international soware project that aims to deliver the best possible user experience.
- 13. . The Ubuntu Promise ‣ Ubuntu will always be free of charge, along with its regular enterprise releases and security updates. ‣ Ubuntu comes with full commercial support from Canonical and hun- dreds of companies from across the world. ‣ Ubuntu provides the best translations and accessibility features that the free soware community has to offer. ‣ Ubuntu’s core applications are all free and open source. We want you to use free and open source soware, improve it, and pass it on. A brief history of Ubuntu Ubuntu was conceived in by Mark Shuleworth, a successful South African entrepreneur, and his company Canonical. Shuleworth recognized Canonical is the company that provides financial and technical support for Ubuntu. It has employees based around the world who work on developing and improving the operating system, as well as reviewing work submitted by volunteer contributors. To learn more about Canonical, go to http://www.canonical.com. the power of Linux and open source, but was also aware of weaknesses that prevented mainstream use. Shuleworth set out with clear intentions to address these weaknesses and create a system that was easy to use, completely free (see Chapter : Learning More for the complete definition of “free”), and could compete with other mainstream operating systems. With the Debian system as a base, Shuleworth began to build Ubuntu. Using his own funds at first, Debian is the Linux operating system that Ubuntu is based upon. For more information visit http://www.debian.org/. installation s were pressed and shipped worldwide at no cost to the recipients. Ubuntu spread quickly, its community grew rapidly, and soon Ubuntu became the most popular Linux distribution available. With more people working on the project than ever before, its core fea- tures and hardware support continue to improve, and Ubuntu has gained the aention of large organizations worldwide. One of ’s open source operating systems is based on Ubuntu. In , the French Police began to transition their entire computer infrastructure to a variant of Ubuntu—a process which has reportedly saved them “millions of euros” in licensing fees for Microso Windows. By the end of , the French Police antici- pates that all of their computers will be running Ubuntu. Canonical profits from this arrangement by providing technical support and custom-built soware. While large organizations oen find it useful to pay for support services, For information on Ubuntu Server Edition, and how you can use it in your company, visit http:// www.ubuntu.com/business/server/overview. Shuleworth has promised that the Ubuntu desktop operating system will always be free. As of , Ubuntu is installed on an estimated % of the world’s computers. is equates to tens of millions of users worldwide, and is growing each year. As there is no compulsory registration, the percentage of Ubuntu users should be treated as an estimate. What is Linux? Ubuntu is built on the foundation of Linux, which is a member of the Unix family. Unix is one of the oldest types of operating systems, and together with Linux has provided reliability and security for professional applica- tions for almost half a century. Many servers around the world that store data for popular websites (such as YouTube and Google) run some variant of Linux or Unix. e popular Android system for smartphones is a Linux variant; modern in-car computers usually run on Linux. Even the Mac is based on Unix. e Linux kernel is best described as the core—almost the brain—of the Ubuntu operating system. e Linux kernel is the controller of the operating system; it is responsi-
- 14. ble for allocating memory and processor time. It can also be thought of as the program which manages any and all applications on the computer itself. Linux was designed from the ground up with security and hardware While modern graphical desktop environments have generally replaced early command-line interfaces, the command line can still be a quick and efficient way of performing many tasks. See Chapter 6: Advanced Topics for more information, and Chapter 2: The Ubuntu Desktop to learn more about GNOME and other desktop environments. compatibility in mind, and is currently one of the most popular Unix-based operating systems. One of the benefits of Linux is that it is incredibly flex- ible and can be configured to run on almost any device—from the smallest micro-computers and cellphones to the largest super-computers. Unix was entirely command line-based until graphical user interfaces (s) emerged in (in comparison, Apple came out with Mac ten years later, and Microso released Windows . in ). e early s were difficult to configure, clunky, and generally only used by seasoned computer programmers. In the past decade, however, graphical user interfaces have grown in usability, reliability, and appear- ance. Ubuntu is just one of many different Linux distributions, and uses one To learn more about Linux distributions, see Chapter 8: Learning More. of the more popular graphical desktop environments called . Is Ubuntu right for you? New users to Ubuntu may find that it takes some time to feel comfort- able when trying a new operating system. You will no doubt notice many similarities to both Microso Windows and Mac as well as some dif- ferences. Users coming from Mac are more likely to notice similarities due to the fact that both Mac and Ubuntu originated from Unix. e Unity shell, which is the default in Ubuntu, is a completely new concept, which needs some exploring to get used to it. See Chapter : e Ubuntu Desktop for more information about the Unity shell. Before you decide whether or not Ubuntu is right for you, we suggest giving yourself some time to grow accustomed to the way things are done in Ubuntu. You should expect to find that some things are different from what you are used to. We also suggest taking the following into account: Ubuntu is community based. at is, Ubuntu is developed, wrien, and maintained by the community. Because of this, support is probably not available at your local computer store. Fortunately, the Ubuntu community is here to help. ere are many articles, guides, and manuals available, as well as users on various Internet forums and Internet Relay Chat () rooms that are willing to assist beginners. Additionally, near the end of this guide, we include a troubleshooting chapter: Chapter : Troubleshooting. Many applications designed for Microso Windows or Mac will not run on Ubuntu. For the vast majority of everyday computing tasks, you will find suitable alternative applications available in Ubuntu. However, many professional applications (such as the Adobe Creative Suite) are not developed to work with Ubuntu. If you rely on commercial soware that is not compatible with Ubuntu, yet still want to give Ubuntu a try, you may want to consider dual-booting. Alternatively, some applications To learn more about dual-booting (running Ubuntu side-by-side with another operating system), see Chapter 1: Installation. developed for Windows will work in Ubuntu with a program called Wine. For more information on Wine, go to http://www.winehq.org. Many commercial games will not run on Ubuntu. If you are a heavy gamer, then Ubuntu may not be for you. Game developers usually design games for the largest market. Since Ubuntu’s market share is not as substantial as Microso’s Windows or Apple’s Mac , fewer game developers allocate resources towards making their games compatible with Linux. If See Chapter 5: Software Management to learn more about Ubuntu Software Center.
- 15. . you just enjoy a game every now and then, there are many high quality games that can be easily installed through the Ubuntu Soware Center. Contact details Many people have contributed their time to this project. If you notice any errors or think we have le something out, feel free to contact us. We do everything we can to make sure that this manual is up to date, informative, and professional. Our contact details are as follows: ‣ Website: http://www.ubuntu-manual.org/ ‣ Reader feedback: feedback@ubuntu-manual.org ‣ : #ubuntu-manual on irc.freenode.net ‣ Bug Reports: https://bugs.launchpad.net/ubuntu-manual/+filebug ‣ Mailing list: ubuntu-manual@lists.launchpad.net About the team Our project is an open-source, volunteer effort to create and maintain qual- ity documentation for Ubuntu and its derivatives. Want to help? We are always looking for talented people to work with, and due to the size of the project we are fortunate to be able to cater to a wide range of skill sets: ‣ Authors and editors ‣ Programmers (Python or TEX) ‣ User interface designers ‣ Icon and title page designers ‣ Event organizers and ideas people ‣ Testers ‣ Web designers and developers ‣ Translators and screenshoers ‣ Bug reporters and triagers To find out how you can get started helping, please visit http://ubuntu-manual. org/getinvolved. Conventions used in this book e following typographic conventions are used in this book: ‣ Buon names, menu items, and other elements are set in boldfaced type. ‣ Menu sequences are sometimes typeset as File ‣ Save As…, which means, “Choose the File menu, then choose the Save As….” ‣ Monospaced type is used for text that you type into the computer, text that the computer outputs (as in a terminal), and keyboard shortcuts.
- 16. 1 Installation Getting Ubuntu Before you can get started with Ubuntu, you will need to obtain a copy of Many companies (such as Dell and System76) sell computers with Ubuntu preinstalled. If you already have Ubuntu installed on your computer, feel free to skip to Chapter 2: The Ubuntu Desktop. the Ubuntu installation image for or . Some options for doing this are outlined below. Minimum system requirements Ubuntu runs well on most computer systems. If you are unsure whether it The majority of computers in use today will meet the requirements listed here; however, refer to your computer documentation or manufacturer’s website for more information. will work on your computer, the Live is a great way to test things out first. Below is a list of hardware specifications that your computer should meet as a minimum requirement. ‣ GHz x processor (Pentium or beer) ‣ of system memory () ‣ of disk space (at least is recommended) ‣ Video support capable of × resolution ‣ Audio support ‣ An Internet connection (highly recommended, but not required) Downloading Ubuntu e easiest and most common method for geing Ubuntu is to download the Ubuntu image directly from http://www.ubuntu.com/download. Choose how you will install Ubuntu: ‣ Download and install ‣ Try it from a or stick ‣ Run it with Windows Download and Install / Try it from a DVD or USB stick For the Download and install, or Try it from a or stick options, select whether you require the -bit or -bit version (-bit is recommended for most users), then click “Start download.” Installing and run alongside Windows For the Run it with Windows option, simply select “Start download,” and then follow the instructions for the Ubuntu installer for Windows. 32-bit versus 64-bit Ubuntu and its derivatives are available in two versions: -bit and -bit. is difference refers to the way computers process information. Comput- 32-bit and 64-bit are types of processor architectures. Most new desktop computers have a 64-bit capable processor. ers capable of running -bit soware are able to process more information than computers running -bit soware; however, -bit systems require more memory in order to do this. Nevertheless, these computers gain per- formance enhancements by running -bit soware. ‣ If your computer has a -bit processor install the -bit version.
- 17. . ‣ If your computer is older, a netbook, or you do not know the type of processor in the computer, install the -bit version. If your computer has a -bit processor, click on the “-bit” option before you click “Start download.” Downloading Ubuntu as a torrent When a new version of Ubuntu is released, the download servers can get Torrents are a way of sharing files and informa- tion around the Internet via peer-to-peer file sharing. A file with the .torrent extension is made available to users, which is then opened with a compatible program such as uTorrent, Deluge, or Transmission. These programs download parts of the file from other people all around the world. “clogged” as large numbers of people try to download or upgrade Ubuntu at the same time. If you are familiar with using torrents, you can download the torrent file by clicking “Alternative downloads,” and then “BitTorrent download.” Downloading via torrent may improve your download speed, and will also be help to spread Ubuntu to other users worldwide. Burning the DVD image Once your download is complete, you will be le with a file called ubuntu- While the 64-bit version of Ubuntu is referred to as the “AMD64” version, it will work on Intel, AMD, and other compatible 64-bit processors. .-desktop-i.iso or similar (i here in the filename refers to the -bit version. If you downloaded the -bit version, the filename contains amd instead). is file is a image—a snapshot of the contents of a — which you will need to burn to a . Creating a bootable USB drive If your is able to boot from a stick, you may prefer to use a memory stick instead of burning a . Scroll down to “Burn your or create a drive,” select or stick, choose the you are using to create the drive, and then click Show me how. If you select the “ Stick” option, your installation will be running from the memory stick. In this case, references to Live , will refer to the memory stick. Trying out Ubuntu e Ubuntu and stick function not only as installation media, but also allow you to test Ubuntu without making any permanent changes to your computer by running the entire operating system from the or stick. Your computer reads information from a at a much slower speed In some cases, your computer will not recognize that the Ubuntu DVD or USB is present as it starts up and will start your existing operating system instead. Generally, this means that the priority given to boot devices when your computer is starting needs to be changed. For example, your computer might be set to look for information from your hard drive, and then to look for information on a DVD or USB. To run Ubuntu from the Live DVD or USB, we want the computer to look for information from the appropriate device first. Changing your boot priority is usually handled by BIOS settings; this is beyond the scope of this guide. If you need assistance with changing the boot priority, see your computer manufacturer’s documentation for more information. than it can read information off of a hard drive. Running Ubuntu from the Live also occupies a large portion of your computer’s memory, which would usually be available for applications to access when Ubuntu is running from your hard drive. e Live / experience will therefore feel slightly slower than it does when Ubuntu is actually installed on your computer. Running Ubuntu from the / is a great way to test things out and allows you to try the default applications, browse the Internet, and get a general feel for the operating system. It’s also useful for checking that your computer hardware works properly in Ubuntu and that there are no major compatibility issues. To try out Ubuntu using the Live / stick, insert the Ubuntu into your drive, or connect the drive and restart your computer. Aer your computer finds the Live / stick, and a quick load- ing screen, you will be presented with the “Welcome” screen. Using your mouse, select your language from the list on the le, then click the buon
- 18. labeled Try Ubuntu. Ubuntu will then start up, running directly from the Live / drive. Figure 1.1: The “Welcome” screen allows you to choose your language. Once Ubuntu is up and running, you will see the default desktop. We will talk more about how to actually use Ubuntu in Chapter : e Ubuntu Desktop, but for now, feel free to test things out. Open some applications, change seings and generally explore—any changes you make will not be saved once you exit, so you don’t need to worry about accidentally breaking anything. When you are finished exploring, restart your computer by clicking Alternatively, you can also use your mouse to double-click the “Install Ubuntu 12.10” icon that is visible on the desktop when using the Live DVD. This will start the Ubuntu installer. the “Power” buon in the top right corner of your screen (a circle with a line through the top) and then select Restart. Follow the prompts that appear on screen, including removing the Live and pressing Enter when instructed, and then your computer will restart. As long as the Live is no longer in the drive, your computer will return to its original state as though nothing ever happened! Installing Ubuntu—Getting started At least of free space on your hard drive is required in order to install Clicking on the underlined “release notes” link will open a web page containing any important information regarding the current version of Ubuntu. Ubuntu; however, or more is recommended. is will ensure that you will have plenty of room to install extra applications later on, as well as store your own documents, music, and photos. To get started, place the Ubuntu in your drive and restart your computer. Your computer should load Ubuntu from the . When you first start from the , you will be presented with a screen asking you whether you want to first try out Ubuntu or install it. Select the language you want to view the installer in and click on the Install Ubuntu buon. is will start the installation process. If you have an Internet connection, the installer will ask you if you would like to “Download updates while installing.” We recommend you do so. e second option, “Install this third-party soware,” includes the Fluendo codec, and soware required for some wireless hardware. If you are not connected to the Internet, the installer will help you set up a wireless connection. e “Preparing to install Ubuntu” screen will also let you know if you have enough disk space and if you are connected to a power source (in case
- 19. . you are installing Ubuntu on a laptop running on baery). Once you have selected your choices, click Continue. Figure 1.2: Preparing to install. Internet connection If you are not connected to the Internet, the installer will ask you to choose a wireless network (if available). We recommend that you connect during install, though updates and third-party software can be installed after installation. . Select Connect to this network, and then select your network from the list. . If the list does not appear immediately, wait until a triangle/arrow ap- pears next to the network adapter, and then click the arrow to see the available networks. . In the Password field, enter the network or key (if necessary). . Click Connect to continue. Figure 1.3: Set up wireless. Allocate drive space is next step is oen referred to as partitioning. Partitioning is the process If you are installing on a new machine with no operating system, you will not get the first option. The upgrade option is only available if you are upgrading from a previous version of Ubuntu. of allocating portions of your hard drive for a specific purpose. When you create a partition, you are essentially dividing up your hard drive into sec- tions that will be used for different types of information. Partitioning can sometimes seem complex to a new user; however, it does not have to be. In
- 20. fact, Ubuntu provides you with some options that greatly simplify this pro- cess. e Ubuntu installer will automatically detect any existing operating system installed on your machine, and present installation options suitable for your system. e options listed below depend on your specific system and may not all be available: ‣ Install alongside other operating systems ‣ Install inside Windows ‣ Upgrade Ubuntu … to . ‣ Erase … and install Ubuntu ‣ Something else Install alongside other operating systems. If you are a Windows or Mac user and you are trying to install Ubuntu for Ubuntu provides you with the option of either replacing your existing operating system altogether, or installing Ubuntu alongside your existing system. The latter is called dual- booting. Whenever you turn on or restart your computer, you will be given the option to select which operating system you want to use for that session. the first time, select the Install alongside other operating systems option. is option will enable you to choose which operating system you wish to use when you computer starts. Ubuntu will automatically detect the other operating system and install Ubuntu alongside it. For more complicated dual-booting setups, you will need to configure the parti- tions manually. Figure 1.4: Choose where you would like to install Ubuntu. Upgrade Ubuntu … to 12.10 is option will keep all of your Documents, music, pictures, and other personal files. Installed soware will be kept when possible (not all your currently installed soware may be supported on the new version). System- wide seings will be cleared. Erase disk and install Ubuntu Use this option if you want to erase your entire disk. is will delete any existing operating systems that are installed on that disk, such as Microso Windows, and install Ubuntu in its place. is option is also useful if you have an empty hard drive, as Ubuntu will automatically create the neces- sary partitions for you. Formaing a partition will destroy any data currently on the partition. Be sure to back up any data you want to save before formaing.
- 21. . Something else is option is for advanced users and is used to create special partitions, or Ubuntu installs a home folder where your personal files and configuration data are located by default. If you choose to have your home folder on a separate partition, then in the event that you decide to reinstall Ubuntu or perform a fresh upgrade to the latest release, your personal files and configuration data won’t be lost. format the hard drive with a file system different to the default one. Aer you have chosen the installation type, click Continue, or Install More information and detailed instructions on partitioning are available at: https://help. ubuntu.com/community/HowtoPartition. Now. Confirm Partition choices and start install If you chose Something else, configure the partitions as you need. Once you are happy with the way the partitions are going to be set up, click the Install Now buon at the boom right to move on. To reduce the time required for installation, Ubuntu will continue the installation process in the background while you configure important user details—like your username, password, keyboard seings and default time- zone. Where are you? Figure 1.5: Tell Ubuntu your location. e next screen will display a world map. Using your mouse, click your geographic location on the map to tell Ubuntu where you are. Alternatively, you can use the drop-down lists below the map. is allows Ubuntu to con- figure your system clock and other location-based features. Click Forward when you are ready to move on. Keyboard layout Next, you need to tell Ubuntu what kind of keyboard you are using. In most cases, you will find the suggested option satisfactory. If you are unsure which keyboard option to select, you can click the Detect Keyboard Layout buon to have Ubuntu determine the correct choice by asking you to press a series of keys. You can also manually choose your keyboard layout from the list of options. If you like, enter text into the box at the boom of the window to ensure you are happy with your selection, then click Continue.
- 22. Figure 1.6: Verify that your keyboard layout is correct. Who are you? Ubuntu needs to know some information about you so it can set up the primary user account on your computer. When configured, your name will appear on the login screen as well as the user menu, which we discuss in Chapter : e Ubuntu Desktop. On this screen you will need to tell Ubuntu: ‣ your name ‣ what you want to call your computer ‣ your desired username ‣ your desired password ‣ how you want Ubuntu to log you in Figure 1.7: Setup your user account. Enter your full name under Your name. e next text field is the name your computer uses, for terminals and networks. You can change this to what you want, or keep the predetermined name. Next is your username, the name that is used for the user menu, your home folder, and behind the scenes. You will see this is automatically filled in for you with your first
- 23. . name. Most people find it easiest to stick with this. However, it can be changed if you prefer. Next, choose a password and enter it into both password fields. When both passwords match, a strength rating will appear to the right that will show you whether your password is “too short,” “weak,” “fair,” or “strong.” You will be able to continue the installation process regardless of your password strength, but for security reasons it is best to choose a strong one. is is best achieved by having a password that is at least six char- acters long, and is a mixture of leers, numbers, symbols, and upper- case/lowercase. Avoid obvious passwords that include your birth date, spouse’s name, or the name of your pet. Login Options Finally, at the boom of this screen you have three options from which to choose regarding how you wish to log in to Ubuntu. ‣ Log in automatically ‣ Require my password to log in ‣ Encrypt my home folder Log in automatically Ubuntu will log in to your primary account automatically when you start up the computer so you won’t have to enter your username and password. is makes your login experience quicker and more convenient, but if privacy or security are important to you, we don’t recommend this option. Anyone who can physically access your computer will be able to turn it on and also access your files. Require my password to login is option is selected by default, as it will prevent unauthorized people from accessing your computer without knowing the password you cre- ated earlier. is is a good option for those who, for example, share their computer with other family members. Once the installation process has been completed, an additional login account can be created for each family member. Each person will then have their own login name and password, account preferences, Internet bookmarks, and personal storage space. Encrypt my home folder is option provides you with an extra layer of security. Your home folder is where your personal files are stored. By selecting this option, Ubuntu will automatically enable encryption on your home folder, meaning that files and folders must be decrypted using your password before they can be accessed. erefore if someone had physical access to your hard drive (for example, if your computer was stolen and the hard drive removed), they would not be able to see your files without knowing your password. If you choose this option, be careful not to enable automatic login at a later date. It will cause complications with your encrypted home folder, and will potentially lock you out of important files.
- 24. Finishing Installation Ubuntu will now finish installing on your hard drive. As the installation progresses, a slideshow will give you an introduction to some of the default applications included with Ubuntu. ese applications are covered in more detail in Chapter : Working with Ubuntu. e slideshow will also highlight the Ubuntu support options: Figure 1.8: Ubuntu community support options. Where to get help for Ubuntu. Aer approximately twenty minutes, the installation will complete and you will be able to click Restart Now to restart your computer and start Ubuntu. e will be ejected, so remove it from your drive and press Enter to continue. Figure 1.9: You are now ready to restart your computer. Wait while your computer restarts, and you will then see the login win- dow (unless you selected automatic login).
- 25. . Login Screen Aer the installation has finished and your computer is restarted, you will be greeted by the login screen of Ubuntu. e login screen will present you with your username and you will have to enter the password to get past it. Click your username and enter your password. Once done, you may click the arrow or press Enter to get into the Ubuntu desktop. Ubuntu’s login screen supports multiple users and also supports custom backgrounds for each user. In fact, Ubuntu automatically will pick up your current desktop wallpaper and set it as your login background. Ubuntu’s login screen also A guest session is also available at the login screen. You can activate this session for guests using your laptop or desktop. lets you select the different environments to login. e login screen allows you to update your keyboard language, volume intensity and enable/disable accessibility seings before you log in to your desktop. It also displays date/time and baery power for laptops. You can also shut down or restart your system from the login screen. Figure 1.10: Login Screen. Ubuntu installer for Windows You can install and run Ubuntu alongside your current installation of Win- dows: . Download the Ubuntu installer for Windows http://www.ubuntu.com/ download/ubuntu/windows-installer . Run the download file . Install Ubuntu Download and run the installer Aer the file, wubi.exe, is downloaded, run the file to start the installation. If a security message appears, click Continue, to proceed with the installation: Installation e Ubuntu Installer will start. Choose and enter a “Username” and “Pass- word.” e password must be entered twice to ensure accuracy. Aer
- 26. Other documents randomly have different content
- 27. Li g n . 153. Ca s t s o f c h a m b e r s o f Na u t i l u s a n d Am m o n i t e . (1 /2 nat.) Fig.1.— Cast in calcareous spar of a chamber of Nautilus. From the London Clay. 2.— Cast of a chamber of Ammonites excavatus. From the Coral Rag. Li g n . 154. Cly m e n i a : 1 /2 nat. Devonian. Fig.1.— Clymenia Sedgwickii. 2.— Front view of the same. 3.— Vertical section of C. striata, showing the siphunculus on the inner edge of each septum. 4.— Suture of C. striata. Clymenia (Lign. 154, Ly. fig. 406).—This genus belongs to the Nautilidæ, and is peculiar to the Devonian deposits. It differs from the allied genera in the siphuncle being situated on the inner margin of the septa. The shell is discoidal, and the septa are very slightly lobed. At Elbersreuth, near Bareuth, in the N. E. of Bavaria, the Devonian strata abound in these shells; thirty-five species have been found, the greater number being peculiar to that locality.
- 28. ORTHOCERA In England they are chiefly found at South Petherwin, Cornwall, and in the Devonshire marbles. (See Phillip’s Pal. Foss. Devonshire.) Orthoceras (straight shell), Lign. 155.—The shells of this genus may be described as Nautili uncoiled and extended in a straight line. They are straight, elongated, chambered shells, with smooth and gently undulated septa, which are concave towards the opening or upper part, and have the siphuncle either central, or not far removed from the centre. The Orthoceratites more especially belong to the ancient Secondary strata. They first appear in the Silurian, and abound in the Devonian and Carboniferous. They vary in size from a few inches to several feet in length, and eight or nine inches in diameter; and in form, from a slender elongated cone, to a short, massy, almost spherical figure, with a contracted orifice. Some examples have been noticed with upwards of sixty cells. Mr. Sowerby figures and describes O. giganteum (Min. Conch. tab. 246), from Scotland, as exceeding seven or eight feet in length; and I discovered on the beach at Brighton, where it had probably been brought by some vessel, among ballast, a fine fragment of the same species, indicating as great a magnitude. Several species are figured, Lign. 155, to show the structure and appearance of these fossils. The casts of the separate cells are often found. The section, fig. 3, from the red marble of Devonshire, beautifully displays the situation of the siphuncle, and the lines of the septa. The shelly siphuncle, which is moniliform (bead- like), or dilated at each chamber, is replaced by white spar; and the membranous internal tube is filled with a dark substance, probably molluskite.
- 29. Li g n . 155. Ort h o c e r at i t e s . Fig.1.— Orthoceras striatum. (Min. Conch.) Devonian. 2.— Orthoceras conicum. Whitby. Carboniferous. 3.— Vertical section of an Orthoceras, showing the central siphon, and the chambers. Devonshire. 4.— Orthoceras laterale. Carb. (Min. Conch.) 5.— Orthoceras gregarium. (Munch. Sil. Syst.) a. One of the septa. b. A portion covered at the upper part by the shell. c. The lower part of the same specimen, displaying the septa. There are some species in which the internal tube, as well as the external, is calcareous, and the two are connected at regular intervals, by radiating, hollow processes. These Orthoceratites have been
- 30. principally obtained from the Silurian limestones, at Lake Huron; they also occur in Ireland. Mr. Stokes, who first investigated their structure, has arranged them in a distinct genus, with the name of Actinoceras (radiated-horn).[413] [413] See Geol. Trans, second series, vol. v. p. 708. Slabs of reddish Devonian limestone, containing Orthoceratites, may be seen in some of the pavements at Hampton Court, and in Chelsea College, which when wet present excellent sections of the enclosed shells. Li g n . 156. Am m o n i t e s f r o m t h e Cr e ta c e o u s Fo r m at i o n . Fig.1.— Ammonites varians. Chalk-marl. Hamsey. 2.— Ammonites Dufrenoyi. 2a.—Shows the keel and septum of the same. 3.— Ammonites lautus. Galt. Folkstone. 3a.—Keel and septum of the same.
- 31. Li g n . 157. Am m o n i t e s c o m m u n i s . Lias. Whitby. Ammonitidæ.—The Ammonites, or Cornua Ammonis (so called from a supposed resemblance to the horns engraven on the heads of Jupiter Ammon), are among the most common and well-known fossils of the British secondary strata. In some districts, as in Yorkshire and Somersetshire, where the Ammonites abundantly prevail, they were noticed in very remote times. Local legends, ascribing their origin to swarms of snakes turned into stone by the prayers of some patron saint, are still extant, and are perpetuated by the name of snake- stones, by which these fossils are provincially known. The Lias, near Whitby, in Yorkshire, contains immense numbers of two or three species, one of which (Am. bifrons) is figured in Lign. 127, fig. 7, and another in Lign. 157. The shells comprehended in this family are either spiral, involute, arched, or straight; their septa are deeply lobed, and have the margins foliated. The siphuncle is dorsal, as shown by the notch in the cast, Lign. 156, fig. 3a. Several hundred species have been described; they are divided into genera which are characterized by essential modifications in the direction of the spire, and the inflections of the septa. Thus, in the Ammonites, Lign. 156, the spire is involute, and all the turns contiguous; in Crioceras (curved-horn), Lign. 160, fig. 2, evolute; in Scaphites, incurved at both extremities, Lign. 162; Hamites, bent like a siphon, or hook, Lign. 161, fig. 1; Turrilites, spiral, round a vertical axis, Lign. 163; and in Baculites, straight, Lign. 161, fig. 2. New genera are continually being added, to embrace modifications of structure which appear to be too important for specific distinctions. I will endeavour to render this arrangement more clear to the student by the following definitions. A straight tube, or horn, of an elongated conical figure, tapering to a point, and having its cavity divided by transverse partitions, which
- 32. AMMONIT septa are not straight, but undulated, and their edges, which fit into the walls of the tube, deeply wrinkled, and the whole series pierced by a pipe running along near the outer margin, would be the model of the shell termed Baculites, Lign. 161, fig. 2, (Bd. pl. xliv. fig. 5;) which may be regarded as a straight Ammonite. A similar shell, gently arched or curved, would be a Toxoceras, Lign. 160, fig. 1; the same tube, bent upon itself, like a siphon, into unequal limbs, not contiguous, a Hamites, Lign. 161 (Bd. pl. xliv. fig. 10); bent and approximate, or anchylosed in a straight line, Ptychoceras, Lign. 161, fig. 4; partially convoluted, the whorls contiguous, and the free end recurved, Scaphites, Lign. 162; the same form, but the spire not contiguous, Ancyloceras, Lign. 160, fig. 3; spirally twisted around an axis, Turrilites, Lign. 163 (Bd. pl. xliv. fig. 14); coiled, but the turns not touching each other, Crioceras, Lign. 160, fig. 2; lastly, coiled up in the form of a disk, all the turns being contiguous, Ammonites. Ammonites. Lign. 156, 157, 158.—Shell discoidal, more or less compressed, whorls of the spire contiguous, and often visible; septa lobed, their margins deeply sinuated; aperture symmetrical, border or lip thickened, often notched and auriculated. Siphuncle dorsal. The student will be able readily to distinguish Ammonites from Nautili by attention to the above definition. The situation of the siphuncle, the foliated or wrinkled edges of the septa, as shown in the cast, Lign. 156, fig. 2; and when these characters are wanting, the arched ribs and elevations, as in figs. 1 and 3, will serve as discriminating features. Like the fossil Nautili, the Ammonites most commonly occur as casts, the shell having been dissolved. Sometimes these consist of semi-transparent calcareous spar, the cast of each cell being distinct, but held together by the interlocking of the foliations of the septa; such examples are of great beauty and interest (see Bd. pl. xlii. figs. 2, 3); they most frequently occur in the limestones of the Oolite. The siphuncle is often preserved, even in the chalk specimens, in which all traces of the shell are lost. In a large Ammonite from, near Lewes, not only the shelly siphuncle remains, but even the internal membranous tube, converted into dark molluskite. Separate portions
- 33. Li g n . 158. Am m o n i t e s Ja s o n . 1 /2 n at . Oxford Clay, Trowbridge, Wilts. a.—Lateral processes of the margins of the aperture of similar siphuncles occur in the chalk, and have been mistaken for tubular shells. The outer lip, or margin of the aperture, is occasionally found entire. In some species there is a dorsal process, as in a very common Chalk Ammonite (A. varians, Lign. 156, fig. 1), which extends far beyond the margin; in other species, from the Oxford Clay, there are long, narrow, lateral appendages, (Lign. 158). In the collection of S. P. Pratt, Esq., there is a small Ammonite, from the Inferior Oolite of Normandy, in which these processes meet over the aperture, leaving only a circular aperture towards the back of the shell (where the siphuncle of the animal would be situated) and a narrow fissure on the side next the involute spire. The specimen is unique, and can scarcely be regarded as a normal form.[414] (Mr. Woodward.) [414] M. Steenstrup has described a species of Purpura, which at the close of its life shuts up the aperture of its shell, with the exception of the respiratory siphon.—Mr. Woodward. From the small size of the cells of the Ammonites, particularly in those species which are of a depressed or flattened form, it was long doubted whether the outer chamber could have been sufficiently capacious to contain the body of the animal; and it was supposed that these shells were internal, like the recent Spirula, or Crosier. But Dr. Buckland has clearly demonstrated, that the outer cell of the Ammonite, if restricted in breadth, is sufficiently ample in length to have contained the soft parts of a Cephalopod, equal in magnitude to the largest known specimens, its proportion to the chambered part being as considerable as in the Nautilus. The outer chamber often occupies more than half, and in some instances the entire circumference of the outer whorl (see Bd. pl. xxxvi.).
- 34. In certain argillaceous deposits, as the Galt, and the clays of the Lias, Ammonites with the shell preserved are abundant; generally the outer opaque layer is wanting, or adheres to the matrix when a specimen is removed, leaving only the internal nacreous, or pearly coat. Folkstone, on the coast of Kent, is celebrated for examples of this kind, which may easily be collected from the Galt, which forms the base of the cliffs, at Eastware Bay. Watchett, in Somersetshire, is equally rich in the pearly Ammonites of the Lias; entire layers of these beautiful organic remains occur in the limestones and in the shale exposed at low water.[415] [415] A splendid group of these Ammonites may be seen in the Gallery of Fossils at the British Museum. The shell of the Ammonite is generally thinner and more delicate than that of the Nautilus. However thin these shells may be, they are possessed of great strength of structure. Not only is the shell one continuous arch, but it is moreover provided with transverse arches or corrugated ribs, which, like the flutings on metal pencil-cases, and corrugated sheet-iron, greatly strengthen the thin material. These ribs are further subdivided, so as to multiply supports as the convexity of the shell enlarges, in a manner somewhat similar to the groin-work of vaulted roofs. The spines, tubercles, and bosses, which often arise from the ribs, are so many additions to the strength of the latter. The sides of the shell are also supported by the transverse plates forming the septa, or divisions of the chambers, and, as these plates are very sinuous where they meet the sides of the shell, they distribute their support over a considerable portion of the surface.[416] These complicated edges of the septa form the delicate and intricate lines of foliation (sutures) seen on the casts of Ammonites (Lign. 156, fig. 2), Baculites (Lign. 161, fig. 3), Hamites, &c. In some species the shell is thick and dense, as in the Ammonites of the Kimmeridge Clay near Aylesbury, in which one species (Ammonites biplex, Min. Conch. pl. ccxciii.) in particular abounds, and is very generally invested with the shell, as perfect as if recent. The same Ammonite occurs in the Portland limestone above, in the state of casts, without any vestige of the shell. In some strata the shell is replaced by calcareous spar; in
- 35. others by silex or flint.[417] In the pyritous clays and shales of the Lias, the shell and all its delicate internal mechanism are coated with or replaced by brilliant sulphuret of iron, forming the most exquisite natural electrotype imaginable. Polished vertical sections of these fossils often exhibit the inner cells filled with transparent white calcareous spar; sometimes with groups of crystals of sulphate of lime. The Ammonites of the Galt, and of the Kimmeridge Clay, are also frequently imbued with the same mineral. [416] See Bd. i. p. 339, &c. [417] See an admirable figure of a chalcedonic specimen, exhibiting the foliated septa of an Ammonite, Bd. pl. xli. There are about two hundred identified species of Ammonite in the British strata, ranging through all the secondary formations; they have not been found in the Tertiary deposits. They vary in size from half an inch to four feet in diameter.[418] [418] I have seen imprints of the large Chalk Ammonite, A. peramplus (Min. Conch. pl. ccclvii.), on the shore off Rottingdean, and Beachy Head, which indicated even larger proportions. Certain species are restricted to particular formations, and are therefore oftentimes of essential aid in determining the relations of a deposit; for example, the Galt contains several species not found in the upper division of the Chalk; and in the Chalk-maid are species that have not been discovered in other strata. Certain Ammonites of the Lias are peculiar to that formation (as A. Walcottii, Lign. 127, fig. 7, p. 397; and A. communis, Lign. 157). Ammonites of species allied to those of our Middle and Lower Oolites have been discovered in strata in the Himalaya mountains, several thousand feet above the level of the sea.
- 36. GONIATITES. CERATITES. CRIOCERA Li g n . 159. Go n i at i t e s . nat. Carb. Syst. Fig. 1.— Goniatites Listeri. 2.— Goniatites striatus. 3.— Outline of a suture of Goniatite. 4.— Outline of a suture of Ammonites venustus. The Arrows in figs. 3 and 4 denote the direction of the dorsal line. Goniatites, Lign. 159.—From the numerous family of Ammonites, a separation has been made of a large division, in which the margins of the septa are not deeply notched or foliated, and are destitute of lateral crenatures or denticulations, so that their outline always presents a continued uninterrupted line. The siphuncle is relatively small. The last or outer cell of the shell extends beyond one turn of the chambered part. The back is occasionally keeled, but in most species is round. In illustration of this genus, which is named Goniatites, I have selected two common species (Lign. 159) from the Carboniferous limestone, and annexed outlines of a suture (the edge of the septum) of a Goniatite, and of an Ammonite, for comparison. The importance of the separation of this type of Ammonites into a distinct genus, relates to the Goniatites being
- 37. restricted to some of the older sedimentary strata; for although there are sixty British species, none of them have been observed above the Carboniferous system.[419] [419] G. Henslowi, G. striatus, and G. sphæricus, are figured in Bd. pl. xl. In Ceratites the sutures are more simple than in the Ammonite, being lobed rather than foliated; and the alternate lobes have their edge crenulated or finely toothed. (C. nodosus, Bd. pl. xl.) This genus is found in the Muschelkalk and the Keuper formations of Europe and Asia. Our limits will not permit us to extend this notice of the very numerous family of Ammonitidæ,[420] except to offer a few illustrations of some of the modifications in form to which we have already alluded, and which will assist the student in discriminating these fossil remains. [420] For further information, Dr. Buckland’s Treatise, and the respective articles in the Penny Cyclopædia, may be referred to. Mr. Woodward’s Manual should be consulted for the classification of the family, and M. D’Orbigny’s Paléontologie Française for the illustration of species. Crioceras (coiled-horn), Lign. 160, fig. 2.—This shell differs from the Ammonites in the turns of the spire being distant from each other. The siphuncle is continuous, and the septa are regularly divided into six lobes. I have found specimens of this genus in the Chalk-marl at Hamsey, and in the White Chalk, near Lewes (Foss. South D. tab. xxiii. fig. 9).
- 38. TOXOCERAS. HAMITE Li g n . 160. Sh e l l s o f t h e fa m i ly Am m o n i t i d æ . Chalk and Greensand. Fig.1.—Toxoceras Emericianum, and its septum. Hamsey. 2.—Crioceras Puzosianum. (M. D’Orbigny.) Lewes. 3.—Ancyloceras furcatum, and its septum. France. In the genus Ancyloceras (incurved horn), Lign. 160, fig. 3, the whorls are separate, and, at first, spiral (like Crioceras); but afterwards the shell is prolonged, and then inflected at the large extremity, like a Scaphite, but the whorls are not contiguous. A very large species of Ancyloceras occurs in the Kentish Rag, near Maidstone, some specimens of which are eighteen inches in length. It is figured and described, by the name of Scaphites Hillsii, in the admirable Memoir of Dr. Fitton on the Strata below the Chalk (Geol. Trans. vol. iv. pl. xv.); the present genus was not then established. The Shanklin Sand in the Isle of Wight also contains a gigantic species, which is figured and described by Mr. J. D. Sowerby, in the Geol. Trans., as Scaphites gigas. Ancyloceras occurs also in the Oolite.
- 39. In Toxoceras (bow-horn), Lign. 160, fig. 1, the shell is slightly curved, like a horn. Two or three species of Toxoceras are found at Hamsey. The tubercles, in the casts, are the bases of spines, with which the back of the shell was armed, as I have ascertained by examples examined in the rock (see Foss. South D. tab. xxiii. fig. 1). The specimens figured of the above two genera occur in the Neocomian strata of France. Hamites (hook-shaped). Lign. 161, fig. 1.—Shell involute, spiral, the turns not contiguous; spire irregular, elliptical; the large end reflected towards the spire. The term Hamite, proposed by the late Mr. Parkinson, was formerly given to all the fragments of sub-cylindrical chambered shells, that were bent, or slightly hooked; and the genera Ancyloceras, Toxoceras, &c., have been separated from them, by M. D’Orbigny. But from fossils recently obtained from Cretaceous strata in Pondicherry, and other parts of India, it seems probable that these genera will be found to merge into each other; at present it is convenient to keep up the distinction. The Hamites are distinguished from Ancyloceras, which they most resemble, by their elliptical, irregular spire. Ptychoceras (folded horn). Lign. 161, fig. 4.—This is another genus formed from the Hamites. The shell is bent double in the shape of a siphon, and the limbs are united together. The specimen figured is from the Neocomian strata of the Lower Alps.
- 40. BACULITE Li g n . 161. Ha m i t e s , e t c . f r o m t h e Ch a l k -m a r l . Fig.1.— Hamites cylindraceus, with part of the shell. (M. D’Orbigny.) 3.— Baculites baculoides, with the mouth entire. Hamsey. 3.— Part of the stem of the same species, showing the sinuous septa. A detached septum is figured above. 4.— Ptychoceras Emericianum. (M. D’Orbigny.) Baculites (staff-like). Lign. 161, figs. 2 and 3.—This, as the name implies, is a straight, elongated, conical, chambered shell; the upper part is destitute of septa, and probably contained the body of the animal.
- 41. SCAPHITE In my early researches in the Chalk-marl of Hamsey, I discovered numerous solid, oval, and cylindrical pipes of marl, with scarcely any vestige of organic structure, whose origin it was impossible to determine. At length I found the specimen, Lign. 161, fig. 2, which showed the perfect aperture of a chambered shell; and afterwards I found portions which displayed the foliated septa. (Foss. South D. tab. xxiii. figs. 5, 6, 7.) The Baculite, when perfect, is elongated to a point; the septa are very numerous and foliated; the siphuncle is situated on the margin. I have a splendid specimen from the Chalk of France, (collected by M. Alex. Brongniart,) which is composed of distinct casts of the cells, held together by the deep inflections of their margins, in the same manner as are the sparry casts of Ammonites, previously described.[421] [421] See Bd. pl. xliv, fig. 5. The Galt, near Folkstone, abounds in fossils of the above genera, principally of Hamites; and the nacreous substance of the shells is very often preserved. From the Chalk-marl near Dover, Southbourn, Ringmer, and Southerham, near Lewes, and from Clayton, near Hurstpierpoint, in Sussex, I have obtained examples of several species. Scaphites (boat-like). Lign. 162.—This name was given by Mr. Parkinson (Org. Rem. vol. iii. pl. x. See Pict. Atlas) to some small chambered shells from the Chalk and Shanklin Sand, of a boat-like form, with the inner whorls coiled up in a spire, and half hidden by the outer chamber, which becomes contracted and recurved on itself, is destitute of septa, and terminates in an oval or transverse mouth. The siphuncle is dorsal. An Ancyloceras closely coiled would be a Scaphite. Hamsey marl-pit yielded to my early researches the first Scaphites discovered in the British strata, together with Turrilites, and other cephalopodous shells, previously unknown in England.[422] The Scaphite is of an elliptical form, the spire and the mouth approaching close to each other; the spire occupies about one-half of the shell. Except the thick outer lip or margin of the aperture, which is almost constantly found changed into pyrites, it is rarely that any vestige of the shell remains. The same mineral constitutes casts of the spiral
- 42. part; and these, when separated from the other portion, might be taken for Ammonites; see fig. 2. There are two varieties at Hamsey; one, with the surface covered by fine transverse striæ, which arise singly from the inner margins, and bifurcate on the dorsal part; fig. 1. The other is also striated, but has a row of prominent ribs on the inner half of the broad central portion of the shell; fig. 4. Scaphites occur in the Upper Green Sand of Dorsetshire, and in the Chalk-marl in several places in England; and at Rouen, in France; and a large species, S. Cuvieri, has been found in New Jersey. [422] Sow. Min. Conch, vol, i. p. 53. Li g n . 162. Sc a p h i t e s . Chalk-marl. Hamsey. Fig.1 and 4.—Scaphites æqualis. (Parkinson.) 2.—Cast in pyrites of the spiral part of a Scaphite. 2a.—Front view of the same specimen. 3.—Front view of Scaphites æqualis.
- 43. TURRILITE Li g n . 163. Tu r r i l i t e s . Chalk-marl. Fig.1.—Turrilites catenatus. (M. D’Orbigny.) France. a.—One of the septa. 2.—Turrilites costatus. Hamsey. Turrilites. Lign. 163.—Shell spiral, more or less conical, coiled obliquely round an axis, and turriculated. Spire sinistral, whorls contiguous, apparent, with a perforated umbilicus. Edges of septa very sinuous. Siphuncle continuous, situated either on the external convexity, or near the suture at the base of the wreath. The discovery of three species of these elegant shells rewarded my researches in the little marl-pit at Hamsey, already noticed, and were the first examples of the genus found in England.[423] Like the Ammonites, Scaphites, Hamites, &c. with which they are associated, the Turrilites of our Chalk-marl seldom possess any traces of their shells. The specimens are solid and tolerably sharp casts, with
- 44. occasional indications of the septa, and more rarely of the siphunculus. They vary in size from two or three inches to two feet in length; and are frequently more or less elliptical, from compression. The three species which generally occur in the Sussex and Kentish chalk, are T. costatus, Lign. 163, fig. 2; T. tuberculatus (Foss. South D. pl. xxiv. fig. 7), characterised by its four rows of tubercles; and T. undulatus (Foss. South D. pl. xxiv. fig. 8), the wreaths of which are ornamented with plain, slightly undulated, transverse ribs. These are all reversed, or sinistral shells; that is, the spire is twisted to the left, the aperture being on the right hand of the observer when the shell is placed on its apex, as in fig. 1. Several other species of Turrilites occur in the Chalk of France,[424] one of which, T. catenatus, is represented Lign. 163, fig. 1. [423] Sow. Min. Conch, tab. xxxvi. [424] See M. D’Orbigny’s Paléontologie Française. Some of the Turrilites attain a considerable magnitude. The largest found in England is a specimen of T. tuberculatus (Min. Conch. tab. lxxiv.), from Middleham, in the parish of Ringmer, near Lewes; when perfect, it must have been full two feet in length: it consists of six wreaths, the siphuncle, in the state of pyrites, appearing in three or four; portions of the nacreous internal layer of the shell remain.[425] In some specimens in my possession, the form of the aperture, and the termination of the columella, are distinctly shown; as in the fine example the last whorl of which is represented in Lign. 164. [425] This specimen is now in the British Museum.
- 45. APTYCHU Li g n . 164. Tu r r i l i t e s t u b e r c u l at u s , (Bosc.) nat. Chalk-marl, Lewes. Showing the form of the aperture, and the spinous tubercles. The specimen is a cast in indurated chalk-marl; the last wreath only is figured. Fig.1. — Posterior view, exhibiting the expanded outer lip, and the obtuse termination of the columella. 2. — Front view, showing the form of the aperture. a.—Two tubercles, bearing spines. The Chalk-marl of Lewes, of the Sussex coast, and of the cliffs near Dover, and the Upper Green Sand of Dorsetshire, have yielded the principal British specimens of this genus. Several species occur in the lower cretaceous strata, at St. Catherine’s Mount, near Rouen, associated, as in England, with Scaphites, Hamites, and other allied genera.[426] [426] See Fossils of the South. Downs for figures of many species of the Cephalopoda of the Sussex Chalk. Aptychus, Meyer. (Trigonellites, Parkinson.) Lign. 165.— Associated with the remains of Ammonites in several localities, are found flattened triangular bodies, from less than an inch to an inch and a half in diameter, the nature of which is still somewhat problematical. A good figure is given by Mr. Parkinson of one species (Org. Rem. vol. iii. pl. xiii. figs. 9, 10, 12. See Pict. Atlas), with the
- 46. Lign. 165. Aptychus sublævis. 1 /2 nat. Kimmeridge Clay, Hartwell, Bucks. Fig.1.— The convex surface. 1a. — Magnified section of portion. 2.— The concave side. DISTRIBUTION OF FOSSIL CEPHALOPOD name Trigonellites latus. These bodies frequently occur in pairs and in apposition, as in the specimen figured in Lign. 165. Their structure is cellular; one surface is slightly concave and striated, and the other covered with minute circular pores. Altogether their appearance is that of bodies enclosed in vascular integuments. It is supposed that they are the opercula of Ammonites. These fossils are commonly found in the last or body chamber of Ammonites, in the Oxford Clay, near Chippenham, the Coral Oolite of Malton, the Lias of Lyme Regis, and the lithographic limestone of Solenhofen. M. Ewald states that they may be found in the Chalk Scaphites by making a longitudinal section of the body chamber: but I have not succeeded in detecting them in the examples from the chalk-marl which I have broken up for that purpose. As these bodies (alluded to by authors as Trigonellites, Aptychus, Munsteria, &c.) will probably come under the observation of the collector, especially among the fossils of the Kimmeridge Clay, these remarks are introduced to suggest diligent research, in the hope that the origin of these fossils may at length be discovered. Geological Distribution of Fossil Cephalopoda.—Even from this short review of the principal types of the fossil Cephalopoda, the great interest which attaches to the study of this class of organic remains is strikingly demonstrated. Their geological distribution is alike replete with phenomena of an important character. In the Lower Palæozoic (Lower and Upper Silurian) strata, the chambered mollusks belong (with a very few doubtful exceptions) to the Nautilidæ, namely, Nautilus, Lituites, Cyrtoceras, Orthoceras, &c. The Devonian and Carboniferous systems contain Nautilus, Clymenia, Gyroceras, Cyrtoceras, and Orthoceras, together with a
- 47. peculiar group of Ammonitidæ, the Goniatites. The Trias in general is extremely poor in Cephalopoda; the Permian group affording but two species of Nautilus, and the Muschelkalk two other species: but, in addition to these, the Muschelkalk contains Ceratites, which is a genus peculiar to the Triassic group, and chiefly abounds in the St. Cassian beds (in the Austrian Alps), where it is accompanied by Nautilus, Orthoceras, Ammonites, and Goniatites. In the Lias and Oolite Nautili abound, and we meet for the first time with Belemnites. The same families, viz. Nautilidæ, Ammonitidæ, and Belemnitidæ, prevail throughout the Cretaceous strata. The Tertiary formations contain a few Nautilidæ only; no vestiges of the Ammonitidæ and true Belemnitidæ, which, as we have seen, swarmed in the ancient seas, are perceptible, while in the existing oceans, the Nautilus and Spirula are the sole representatives of the numerous shell-bearing cephalopoda of the ancient geological eras. Thus, the Nautilidæ extend from the oldest to the newest fossiliferous strata, the genus being still in existence: the Ammonitidæ, on the other hand, though less ancient in origin, do not pass beyond the limits of the cretaceous epoch. In the following tabular arrangement these facts are placed in a more distinct point of view:— Tabular View of the Distribution of Cephalopoda through the Geological Epochs. Existing Genera Argonauta. Octopus, &c. Octopoda. Dibranchiata. Loligo, Cranchia. Sepiola, Onychoteuthis, &c. (Teuthidæ). Decapoda. Sepia (Sepiadæ). Spirula. Nautilus (Nautilidæ). Tetrabranchiata.
- 48. General fossil in the Tertiary Formations Sepiadæ Sepia, Spirulirostra, Beloptera, Belemnosis. Nautilidæ Nautilus and Aturia Cretaceous Deposits Belemnitidæ Belemnites, Belemnitella, and Conoteuthis. Nautilidæ Nautilus. Ammonitidæ Ammonites, Crioceras, Scaphites, Ancyloceras, Toxoceras, Hamites. Ptychoceras, Helicoceras, Turrilites, Baculites. Oolite and Lias Sepiadæ Sepia. Teuthidæ Teudopsis, Beloteuthis, Geoteuthis, Leptoteuthis, Ommastrephes. Belemnitidæ Belemnites. Acanthoteuthis, and Belemnoteuthis. Nautilidæ Nautilus. Ammonitidæ Ammonites, Ancyloceras. Trias Nautilidæ Nautilus. Ammonitidæ [427] Ammonites, Goniatites, and Ceratites. Carboniferous System Nautilidæ Nautilus, Gyroceras, Cyrtoceras, Gomphoceras, and Orthoceras, Actinoceras, &c. Ammonitidæ Goniatites. Devonian System Nautilidæ Nautilus, Clymenia, Cyrtoceras, Phragmoceras, Gomphoceras, Orthoceras, Actinoceras, &c. Ammonitidæ Goniatites. Upper and Lower Silurian Systems Nautilidæ Nautilus, Lituites, Gyroceras, Cyrtoceras, Phragmoceras, Gomphoceras, Oncoceras, Ascoceras, Orthoceras, Actinoceras, &c. [427] The Ammonitidæ are from the St. Cassian beds only.
- 49. With regard to the zoological affinities between the living and extinct species of testaceous Cephalopoda, Dr. Buckland remarks, "that they are all connected by one plan of organization; each forming a link in the common chain which unites the existing species with those that prevailed among the earliest conditions of life upon our globe; and all attesting the identity of the design that has effected so many similar ends, through such a variety of instruments, the principle of whose construction is, in every species, fundamentally the same. "Throughout the various living and extinct genera of these beings, the use of the air-chambers and siphuncle of their shells, to adjust the specific gravity of the animals in rising and sinking, appears to have been identical. The addition of a new transverse plate within the coiled shell added a new air-chamber, larger than the preceding one, to counterbalance the increase of weight that attended the growth of the shell and body of these animals." (Bd. p. 380.) The occurrence of the Nautilus, and its congeners, among the earliest traces of the animal kingdom, and their continuance throughout the immense periods during which the family of Ammonitidæ was created, flourished, and became extinct, and the existence of species of the same genus at the present time, are facts too remarkable to have escaped the notice even of those who are not professed cultivators of geological science; and I am induced to quote the following beautiful lines, by Mrs. Howitt, to impress this interesting phenomenon more strongly on the mind of the youthful reader.[428] [428] The poetess has, however, not been literally accurate regarding the Nautilus and its habits, nor as to the formation of stratified rocks, but has given a romantic rather than a scientifically correct view of this interesting Cephalopod, and of the disappearance of its congener. The young reader must, therefore, remember that the Nautilus sometimes floats, but never sails; and that the whole race of Ammonites died out in course of time, and were not annihilated by convulsive movements of earth and sea. "TO THE NAUTILUS. "Thou didst laugh at sun and breeze,
- 50. ON COLLECTING FOSSIL CEPHALOPOD In the new created seas; Thou wast with the reptile broods In the old sea solitudes, Sailing in the new-made light, With the curl’d-up Ammonite. Thou surviv’dst the awful shock, Which turn’d the ocean bed to rock, And changed its myriad living swarms, To the marble’s veined forms. "Thou wast there, thy little boat, Airy voyager! kept afloat, O’er the waters wild and dismal, O’er the yawning gulfs abysmal; Amid wreck and overturning, Rock-imbedding, heaving, burning, Mid the tumult and the stir; Thou, most ancient mariner, In that pearly boat of thine, Sail’dst upon the troubled brine." On the Collection of British Fossil Cephalopoda.—In the Tertiary formations of England, the remains of but seven species of Nautilus (comprising Aturia) have been noticed; the large species (N. imperialis) is the most common. These are generally in a good state of preservation, and only require the careful removal of the surrounding clay or marl. When pyrites largely enters into the composition of the specimens, the investing matrix can seldom be effectually cleared off: if the outer surface, and general form, be not well displayed, breaking the specimen will often expose the inner cells, with the siphunculus, in a beautiful state. The Nautilus imperialis is occasionally imbedded in the septaria of the Isle of Sheppey, and of Bognor and Bracklesham, on the Sussex coast. Sections of such examples, in the vertical direction of the enclosed shell, afford, when polished, very brilliant and interesting fossils; the septa and the shelly tube of the siphunculus are often preserved.
- 51. The Cephalopods of the Cretaceous formation, with the exception of those in the argillaceous strata of the Galt, are generally destitute of their shells, and only occur in the state of casts; and the Chalk Nautili are liable to separate at the divisions of the septa, and an entire series of the casts of the chambers may sometimes be obtained, so as to display the entire form of the original shell. The Ammonites of the White Chalk, although mere casts, yet retain their configuration, the foliated margins of the septa dove-tailing them together. I have already mentioned that search should be made along the back of these specimens for the siphuncle, the shelly tube of which is sometimes well defined. In the Chalk-marl the casts are sharper than in the White Chalk, and generally of a deep ochreous colour, with the lines of the sinuous septa clearly defined. The siphuncle is occasionally preserved in pyrites, in the Ammonites, Nautili, Turrilites, and Scaphites; and the outer lip or margin of the mouth, or aperture, of the latter, and of the Ammonites, is frequently replaced by the same mineral. The Ammonites, Hamites, &c. of the Galt have their pearly coat remaining, but this investment is extremely delicate; and although when first removed from the marl it is beautifully iridescent, the vivid hues are very evanescent, and the shell becomes opaque and of a light fawn colour. Very commonly the shell flakes off, wholly or in part, leaving a cast of indurated pyritous marl. I have preserved specimens with the shell many years, by applying a thin coat of mastic varnish with a soft camel-hair pencil, before the marl had become dry, and while the shells were entire. The Galt Ammonites, like the Nautili of the London Clay, are often invested with pyrites, and have the inner cells and siphuncle well preserved. The argillaceous strata of the Oolite and Lias contain Ammonites, &c. in much the same state of mineralization as those of the Galt. The Kimmeridge Clay, in some localities, particularly around Aylesbury (and especially at Hartwell Park, the seat of Dr. Lee), abounds in Ammonites with the shell as perfect and beautiful as if just dredged up from the sea. But, like the fossils of the Galt, few of the specimens are durable; although in many examples the shell may be preserved by the application of mastic varnish. The most common Ammonite at Hartwell
- 52. is A. biplex (Sow. Min. Conch.), which varies from three inches to one foot in diameter; the surface is covered by very strong ribs that encircle the whorls. The shell is thick, and composed of several laminæ.[429] [429] According to the observations of my son, the outer layers, when highly magnified, present an appearance of opaque areolæ, with irregular radiating fibres; the inner laminæ are covered with minute pores, apparently the orifices of tubuli, some of which are arranged singly in crescents, and others are confluent, like short strands of beads. I mention the fact to direct attention to the microscopic examination of the structure of these splendid fossils. The sparry casts of the separate cells of Ammonites which occur in some of the calcareous beds of the Oolite, will not fail to be observed by the collector. It is convenient to preserve such specimens either on a tray or board, in which a groove is made for their reception, or in a mould of gutta percha. In collecting Belemnitidæ, the caution already given, of examining the surrounding clay or marl, must not be disregarded; the student should remember, that traces of the soft parts of the animals, even of mere impressions of the body and head, with the tentacula and their acetabula, or little horny rings and hooks, are more important than the most splendid examples of the spathose durable osselet. The guards should be selected with especial reference to their containing the phragmocone (see Lign. 141, fig. 2), or chambered conical shell, in the alveolus or cavity of the upper and larger end. An apparently worthless fragment of a Belemnite will often be found to possess this part of the structure, as in the example figured, which, until fractured longitudinally, had been thrown by among useless duplicates. The search for the remains of the fossil naked Cephalopoda, as the Teuthidæ and Sepiadæ, and their ink-bags, must be made in a like cautious manner. In the Lias marls, the ink-bag and its duct is often found partially covered by a pellicle of nacre, without any trace of the other parts of the animal. A reference to Dr. Buckland’s plates (Bd. pl. xxviii. xxix) will familiarize the student with the appearance of these fossil remains.
- 53. LOCALITIES OF FOSSIL CEPHALOPOD A FEW BRITISH LOCALITIES OF FOSSIL CEPHALOPODA. Abingdon, Berks. Ammonites, fine casts in spar and limestone; Middle Oolite. Aylesbury, Bucks. Ammonites, several species; splendid examples of A. biplex, with the shell remaining, in the Kimmeridge Clay. Aymestry. Upper Silurian; Gomphoceras, Orthoceras, &c. Bath. Fine Ammonites in the Oolite. Beachy Head. Along the shore, gigantic Ammonites in the Chalk, at low-water. Benson, Oxfordshire. Fine Hamites, in Chalk-marl. Blackdown, Devonshire. Beautiful siliceous casts of Ammonites; Green Sand. Bognor, Sussex. Nautili, in the Tertiary Clays and sandy Limestones; also, along the neighbouring coast, in Septaria. Bolland, Yorkshire. Mountain Limestone; Goniatites. Boreham, near Warminster, Wilts. Nautili and Ammonites in Green Sand. Bracklesham Bay, Sussex. Nautili in Tertiary Clay. Bridport, Dorset. Ammonites; Inferior Oolite. Brighton. In the Chalk, Ammonites, Belemnitellæ, &c. Brill, Lucks. Ammonites, as at Aylesbury. Buxton, Derbyshire. Goniatites; Mountain Limestone. Charmouth, Dorsetshire. Ammonites, Belemnites, &c.; Lias.
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