10 



REPTILES. 



it seizes birds, reptiles, &c., devours tlie young Alligators, and 

 devoured in turn by the old ones. Its flesh is good food* (a). 



* Add, Trioni/x javanicus, Geoff. Ann. du Mus. XIV;— 7V. c«ri»n/MS, Id.; — Tr. 

 stelUitiis, Id.;— yy. euphrutiais, Olivier, Voy. en Turqiiie, &c. pi. xlii;— Zr. ^ange- 

 ticiis, Du\imce];~Tr. grmiosiis, Leach, or Test graiwsa, Sclioepf. xxx, A and B. 



N. B. The TortHc de Bnrlrnm, Voy. Am. Sept. tr. fr. I, pi. 2, appears to me to 

 be the T. fervx, to which, through a niistAe, two nails too many have been udded 

 to each foot. 



^f° (a) The Turtles form a very interesting feature in the verj' curious branch 

 of Zoolo<;y connected with fossil animals. Tlie remains which .-ire found of them 

 in the fossil state are, in general, portions of the bony skeleton. In the Tilgate 

 Forest strata, remains have been found consisting altogether of bones, such as 

 ribs, completely separated from the stenium and vertebrae, vertcbriE isolated, por- 

 tions of the sternum, pelvis, and of the femur, with the tibia, libula, &c., and also 

 of the humerus, with the radius, ulna, &c. These bones are of a dark brown colour, 

 ■whicli n)ay be accounted for by the iron with which they are strongly ini.prcgnati d; 

 and their specific gravity, which is considera"ble, is also a proof of the presence of 

 iron; they are very brittle. The cellular nature of their structure, as seen in some 

 specimens in the magnificent muse im of Mr. Mantell, in Lewes, is displayed in 

 a most interesting manner by the white substance (as carbonate of lime) which is 

 injected, and which is in many specimens seen completely to occupy the medullary 

 cavities of the long bones, such as the femur, humerus, &c. No considerable portion 

 of the shell has been found. 



Remains of a species of the soft-shelled Turtles, (Trionyx), have been also found 

 in Tilgate Forest. Mr. Mantel], as a tribute of respect to Mr. Bakewell, the author 

 of one of the most popular elementary works on Geology in the English language, 

 gives it the name of Trionyx Bakewelli. Though the remains are undoubtedly 

 traceable to this subgenus, yet it differs in some respects from the modern Trionices. 

 Thus, the latter have the intervals between the ribs not ossified; their extremities are 

 not articulated to an osseous border; their surface is shagreened — is marked with 

 minute pits for attaching their only integument, the soft skin. They are without 

 scales (see the early part of the description of Trionyx above), and on the bones 

 accordingly, we find no marks of the margins of those scales which, in other sub- 

 genera, produce depressions and furrows. Now the fossil species, the Triony.x 

 Bakewelli, has a shagreen surface like the modern soft-shelled Turtles, but it difiers 

 from them in having on several of its bones, as the rib and sternum, the impressions 

 of a scaly covering. 



Bones of a species of fresh-water Turtles were found by this justly celebrated 

 geologist, (Mr. Mantell, of Lewes), in the beds of Tilgate Forest. This gentleman 

 sent, a few years ago, some Sussex fossils of this species to Cuvier, which turned o'lt 

 to be portions of the sternum (carapace). Cuvier described them as portions of a flat 

 but unknown species of the genus. Specimens very closely resembling it have been 

 discovered in the Jura limestone near Soleure, and it corresponds with a specimen 

 figured in the 5th vol. of Cuvier's grand work on the " Fossil Bones." But the 

 species with plates and ribs are the most abundant in the Tilgate strata. Other 

 bones have been likewise discovered, which are believed by Mr. Mantell to have be- 

 longed to the Marine Tortoises. The ribs in his Museum, which are supposed to 

 be remains of these marine animals, have a smo ith surface, are equal in width 

 throughout their length, with extremities pointed, striated and marked with impres- 

 sions of scales. There are also found in the strata of this forest, portions of a 

 smooth osseous border, and sternal jilates with margins either radiated or dentated. 

 Mr. Mantell has recently received from Tilgate, a fine .ipecimen of the third sternal 

 plate of a Turtle, which bears a striking resemblance to that of Testudo Imbricata. 

 I'rom the numerous fragments of turtle bones preserved in the Museum of this 

 meritorious naturalist, but which are too imperfect to form the foundation of any 

 very decided conclusions, Mr. Mantell s.ays, that this inference can, however, be 

 drawn, that the strata of Tilgate contains the remains of at least three distinct kinds 

 of Turtle, riamely, a fresh- water species, Tri(.nyx; an unknown .species of Emys; 

 and a marine species of the subgenus Chelonia. 



The whole of the above remains have been found in the upper strata of the chalk 

 formations, which constitute a portion of those called the Secondary Formations. — 

 Eng. Ed. 



