462 Miscellaneous. 



Gavial. In Tel. brevior and in Tel. latifronsy the rami unite to form 

 a symphysis as extended as in the Gavial ; but in some other species, 

 Tel. temporalis^ e. g., the free portion of the ramus is longer. 



The teeth of the Teleosauri are more numerous, more slender, less 

 compressed and more sharply pointed, than in the Gavial ; they are 

 slightly recurved, and the enamelled crown is traversed by more 

 numerous and better defined longitudinal ridges, two of which, on 

 opposite sides of the crown, are more produced than the rest. The 

 fang is smooth, cylindrical, and always excavated at the base. 



The teeth of the Steneosauri are thicker in proportion to their 

 length, and larger and fewer in proportion to the jaws ; but their 

 transverse section is also, as in Teleosauri^ more circular, or less 

 elliptic, than in the Gavial. In both genera of Liassic and Oolitic 

 Crocodiles, the teeth have a closer resemblance to those of the Notho-, 

 Pisto-, and Plesio-saurus than the teeth of modern Gavials have. In 

 these the modification consists in the compression of the crown, 

 rendering the opposite ridges trenchant edges. 



In Teleosaurus Chapmanni I have counted ^g_^g =188 teeth: in 



3Q 32 30 30 



Tel. latifrons ^^z^='^^^ teeth: in Tel. Egertoni 5^z^=154 : 

 Cuvier has assigned to the Tel. Cadomensis ^^3^=180 teeth. The 



above formulae will not be found constant in different individuals of 

 the same species, by reason of the uninterrupted and irregular 

 shedding and replacement of the teeth ; but the numbers indicated 

 in the British fossils are those of the sockets, some of which always 

 appear empty. When these, however, have been scrutinized, they 

 have given evidence that the same law regulated the succession of 

 the teeth at the ancient period when Crocodilians prevailed in 

 greatest numbers and under the most varied generic and specific 

 modifications, as at the present day, when they are reduced to a single 

 procoelian family, forming, as Linnaeus believed, a small section of 

 his genus Lacerta. 



Comparing, agreeably with the principle which has governed my 

 illustrations in the present Course of Lectures, the present and past 

 forms of Crocodilians, I would say that, in the modern Gavial, 

 the two lower processes of the basioccipital have become blended 

 into one descending mass of bone : the paramastoid has been deve- 

 loped at the expense, as it would seem, of the paroccipital process. 

 The basi- and ali-sphenoids become contracted, and cease to pre- 

 sent those proportions of the external surface which they do in the 

 more typical Teleosaurian skull : the parietal, by way of compensa- 

 tion, descends lower down the temporal fossae ; but it is much re- 

 stricted in length, and more flattened above. Every trace of those 

 vacuities which hold the position of the pair of nostrils in the Plesio- 

 saur has disappeared in modern Crocodilia. Their sole external nasal 

 aperture is somewhat raised upon the upper surface of the end of the 

 snout, so that, with the head parallel with the surface of the stream, 

 the nostril alone can be raised to inhale air, or can be lifted out of 

 the water at the same time that the high-placed prominent eye is 



