156 PETRIFACTIONS AND THEIR TEACHINGS. ^CHAP. III. 



and in the modifications of the form of the episternal, hyos- 

 ternal, and hyposternal bones, this species offers the nearest 



LIGN. 33. DISTAL EXTREMITY OF THE RIB OF A TURTLE. TILGATE FORKST. 



(Nat. size) 

 (CHELONIA BELLii. 1 ) 



a. Apical extremity of a rib. 



b. Distal portion of a costal plate. 



resemblance to the Chelone planimentum of the Harwich 

 eocene clay. 



EMYDIANS, or Freshwater Turtles, (Platemys Mantelli.) 

 Wall-case A-B. Of this group of Chelonians, in which the 

 carapace is much flatter than in the land or marine Turtles, 

 there are the remains of a species which Baron Cuvier (to 

 whom I transmitted specimens in 1820) supposed to be 

 identical with one discovered in the Jura limestone at So- 

 leure by M. Hugi, and described in " Ossemens Fossiles" 

 tome v. p. 232. The proportions of the fragments discovered 

 indicate the breadth of the carapace to have exceeded twenty 

 inches. A fine plate of the plastron, the left hyposternal, 2 



1 Named in honour of the eminent zoologist, Thomas Bell, Esq. 

 Secretary of the Eoyal Society. 



2 Marked No. 2338 on the specimen, and labelled in my museum, 

 " Sternal plate of a Marine Turtle," belongs to this species, according 

 to the observations of Professor Owen. 



