Intestinal Structure of Fossil Fishes.

Discoveries have recently been made of Coprolites derived from fossil fishes. Mr. Mantell has found them within the body of the Macropoma Mantellii, from the chalk of Lewes, placed in contact with the long stomach of this voracious fish: the coats of its stomach are also well preserved.* Miss Anning also has discovered them within the bodies of several species of fossil fish, from the lias at Lyme Regis. Dr. Hibbert has shown that the strata of fresh-water limestone, in the lower region of the coal formation, at Burdie House, near Edinburgh, are abundantly interspersed with Coprolites, derived from fishes of that early era; and Sir Philip Egerton has found similar focal remains, mixed with scales of the Megalichthys, and fresh-water shells, in the coal formation of Newcastle-under-Lyne. In 1832, Mr. W. C. Trevelyan recognized Coprolites in

* See Mantell's Geol. of Sussex, Pl. 38. I learn from Mr. Mantell, that the form of the Coprolites within the Macropoma most nearly resemble those engraved, Pl. 15, Figs. 8, 9, of the present work he also conjectures that the more tortuous kinds, (Pl. 15, Figs. 5, 7), long known by the name of Juli, and supposed to be fossil fir cones, may have been derived from fishes of the Shark family, (Ptychodus) whose large palatal teeth (Pl. 27. f) abound in the same localities of the chalk formation with them, at Steyning and Hamsey.

the centre of nodules of clay ironstone, that abound in a low cliff composed of shale, belonging to the coal formation at Newhaven, near Leith. I visited the spot, with this gentleman and Lord Greenock, in September, 1834, and found these nodules strewed so thickly upon the shore, that a few minutes sufficed to collect more specimens than I could carry; many of these contained a fossil fish, or fragment of a plant, but the greater number had for their nucleus, a Coprolite, exhibiting an internal spiral structure; they were probably derived from voracious fishes, whose bones are found in the same stratum. These nodules take a beautiful polish, and have been applied by the lapidaries of Edinburgh to make tables, letter presses, and ladies' ornaments, under the name of Beetle stones, from their supposed insect origin. Lord Greenock has discovered, between the lamina of a block of coal, from the neighbourhood of Edinburgh, a mass of petrified intestines distended with Coprolite, and surrounded with the scales of a fish, which Professor Agassiz refers to the Megalichthys.

This distinguished naturalist has recently ascertained that the fossil worm-like bodies, so abundant in the lithographic slate of Solenhofen, and described by Count Münster in the Petrefacten of Goldfuss, under the name of Lumbricaria, are either the petrified intestines

of fishes, or the contents of their intestines, still retaining the form of the tortuous tube in which they were lodged. To these remarkable fossils he has given the name of Cololites. (Pl. 15' is copied from one of a series that are engraved in Goldfuss. Petrefacten, Pl. 66.) He has also found similar tortuous petrifactions within the abdominal cavity of fossil fishes, belonging to several species of the genus Thrissops and Leptolepis, occupying the ordinary position of the intestines between the ribs.* (See Agassiz Poissons Fossiles, liv. 2, Appendix, p. 15.)

As these Cololites are most frequently found insulated in the lithographic limestone, M. Agassiz has ingeniously explained this fact by observing the process of decomposition of dead fishes in the lakes of Switzerland. The dead fish floats on the surface, with its belly upwards, until the abdomen is so distended with putrid gas, that it bursts: through the aperture thus formed the bowels come forth into the water, still adhering together in their natural state of convolution. This intestinal mass is soon torn from the body by the movement of the waves; the fish then sinks, and the bowels continue a long time floating on the water if cast on shore, they remain many days upon the sand before they are completely decomposed. The small bowels only are thus detached from the body, the stomach and other viscera remain within it.

We owe this illustration of the nature of these fossil bodies, whose origin has hitherto been inexplicable, to the author of a most important work on fossil fishes, now under publication at Neuchatel. His qualifications for so great and difficult a task are abundantly guaranteed by the fact, that Cuvier, on seeing the progress he had made, at once placed at the disposal of Professor Agassiz the materials he had himself collected towards a similar work.

It is probable that to many persons inexperienced in anatomy, any kind of information on a subject so remote, and apparently so inaccessible, as the intestinal structure of an extinct reptile or a fossil fish, may at first appear devoid of the smallest possible importance; but it assumes a character of high value, in the investigation of the proofs of creative wisdom and design, that are unfolded by the researches of Geology; and supplies a new link to that important chain, which connects the lost races that formerly inhabited our planet, with species that are actually living and moving around ourselves.* *The systematic recurrence, in animals of such distant eras, of the same contrivances, similarly disposed to effect similar purposes, with analogous adaptations to peculiar conditions of existence, shows that they all originated in the same Intelligence.

When we see the body of an Ichthyosaurus, still containing the food it had eaten just before its death, and its ribs still surrounding the remains of fishes, that were swallowed ten thou

Le temps qui répand de la dignité sur tout ce qui échappe à son pouvoir destructeur, fait voir ici un exemple singulier de son influence ces substances si viles dans leur origine, étant rendues à la lumière après tant de siècles, deviennent d'une grande importance puis qu'elles servent à remplir un nouveau chapitre dans l'histoire naturelle du globe.-Bulletin Soc. Imp. de Moscow, No. VI. 1833, p. 23.

sand, or more than ten times ten thousand years ago, all these vast intervals seem annihilated, time altogether disappears, and we are almost brought into as immediate contact with events of immeasurably distant periods, as with the affairs of yesterday.

SECTION VI.

PLESIOSAURUS.*

WE come next to consider a genus of extinct animals, nearly allied in structure to the Ichthyosaurus, and co-extensive with it through the middle ages of our terrestrial history. The discovery of this genus forms one of the most important additions that Geology has made to comparative anatomy. It is of the Plesiosaurus, that Cuvier asserts the structure to have been the most heteroclite, and its characters altogether the most monstrous, that have been yet found amid the ruins of a former world.† To the head of a Lizard, it united the teeth of a Crocodile ; a neck of enormous length, resembling the body of a Serpent: a trunk and tail having the proportions of an ordinary quadruped, the ribs of a

* See Pl. 16, 17, 18, 19.

+ Cet habitant de l'ancien monde est peut-être la plus hétéroclite et celui de tous qui paroît le plus mériter le nom de monstre. -Oss. Foss. V. Pt. 2, p. 476.