' ■ Kl
3()
construction and—in some measure—office of the mastoidean and temporal bones; tho position of the
tympanals, and the median frontal foramen—wiiich was closed probably by a horny nipple like tliat of
other fossil reptiles and of some recent ones;—are charactei-s peculiar to tlic head of Ichthyosauri.
But the jaws are furnislied with teeth like crocodiles and the under one has like the subject of
comparison, dental foramina at its posterior external paries:—while six bones identify the Ichthyosaurian
jaw willi that of laccrta and thus it is impossible to say whether its ton|iie was incxtensiblo as the
crocodile's or motive like those of chameleons and other lizards.
Moreover, tlic skull lias tlic temporal cavities of crocodiles, parietal bones like those of the iguana,
and the eye sclerotic plates as the tortoise, chameleon and iguana: the ear was simple and closed
(probably) by fleshy lips like that of crocodiles. To these observations and comparisons 1 liavc to add
that squamous sutures mark every bone—reminding us of the sliding cartilages of some fish;—scarcely
a .¡'’ffgcd edge—a dove-tai! conjunction, is found tliroughout the sivcleton of Ichtliyosauri.
V. The toad, ornythory-nclnis and Iclithyosaurus liavc a thvce-boncd breast and the sternal
mechanism of some birds is refcvrablc to Uie same observation, but taken allogctlicr the sternum of
Iclitiiyosauvi is as much siit generis as the paddles, which wc proceed to examine.
VI. The paddles distinguish Ichthyosauri particularly; they r c those of cctacea but in o
¡lavticular—that of being whole externally; their better relation with clielonia is cstablislicd by their
common number but they arc without claws. The anterior paddles are incrodibiy long in proportion (o
the size of the animal: tlieir cxtraoixlinary length rendered the hinder ones unnecessary except as
assistant rudders to the tail—these arc diminutive therefore and comparatively powerless a
0 exquisitely adapted
VII. Tho vertebrae of Ichthyosauri much resemble those of the shark and wc
to assist in the pursuit of prey; their inverted cones filled with synovia, and t ...................
seconded tlic true swimming apparatus most efTcctivcly and secured tlic utmost freedom of motion.
Tims much then for the anatomical analogies and self-possessed organic principles that render
Ichthyosauri a subject of such intense interest and curiosity.
VIII. As the many great analogies between the Ichthyosaurus, and crocodiles, lacerta and fish,
establish its physiology:—so its situation in the lias determines its habitat.
But crocodiles have scales, are palmate and armed with claws, and some of them exist a groat deal
upon land; iguanas arc wholly tciTcstrial, and tortoises—with a head and liocly totally unlike tliosc of
Iclitliyosaiiri-have scarcely a tail. As for ornythorynchi—which lay eggs like birds and suc'klc theii-
young like maramifers—you would not solve a riddle by putting it in apposition with another:-and then
tlie batracUia and fish have such a diversity of structure and of habits that comparisons witli them afford
but littlo instruction.
True: but look at the Ichthyosaurus in the aggregate and these difficulties vanish. With such
teeth it must have been carnivorous: with that body and those immense oars an inhabitant of water;
tliose slender ribs indicate how little it was fitted for tho land: and the fmcal remains, drawn in plate
twenty-seven and twenty-eight, arc full of the indigestible scales of fish, their food. Ammonites and
pentacrinites, creatures that had their haunt in the deepest oceanic abysses, found in the same bed,
prove tlicm to bave been marine.
But tvli, not ilovial: do wo not find a t Whitby bono« ot ciocodiloa, r,esh-wator tnoliuso's and
bouldcre with Ichthyosauri ?
The lias at Whitby sets all geological ratiocination at defiance: even the simple view I have taken of
Its general character is liable to objection—one celebrated geologist told me that lie would sooner bclicvo
tliat those frcsli-watcr i-cmains came therc by miracle than that llierc were lands sufficiently elevated at
that period to support such a large current as they imply. But if our notion of a disembogued river be
incorrect these crocodiles and molluscs lived in salt water or else tlie ammonites and plagiostoma and
ostrm, pcctens and pentacrinites-found with them-livcd in fresh! Thus geognosist and oryctologist
flounder upon the Lamarkian licrcsy—for what? to disprove a pliysical universality 11
Tho lias of Central Somerset decides the question: that deposit contains no organic remain that has
reference to tlie green earth or meandering stream save a junk or ttvo of wood. The myriad generations
of the former sea that reposed its broad bosom there upon tliat blood-colored plain of the icd-niarl
lived-like the posterity of Ham—secure in their own element, basking in the beams of a more than
Arabian su n :-th c ir briny wilderness charnels not the bones of a strangor-thc inhospitable waste of
world and water there was sacred to the uncouth and savage aborigines, and to them alone.
REV. WILLIAM DANIEL CONYBEARE, M. A.
F.R.S. & G.S.
I.'JSTIT. HEG. SOC. PARIS. COURESP.
iS-e- i-c. çf'c.
TH IS BOOK
P L E S I O S A U R U S
5 e In a c r ilip îr ,
WITH THE AUTHOR'S PROFOUND RESPECT,
AND MOST GRATEFUL ATTACHMENT.