224 FOSSIL REPTILES. 



codiles and caymans. These communicate with the nasal 

 canal only, by a hole of moderate size. These vesicae are not 

 observable in the little gavial, and the Baron considers them 

 the result of age, as he has found this part much more swelled 

 in the old than in the young individuals of Gangeticus, In 

 this respect it presents an additional analogy with the sphenoidal 

 sinuses. 



The lower jaw of the gavial, independently of its elongation, 

 which corresponds with that of the muzzle, has this peculiarity, 

 that its symphysis predominating as far as the last tooth, the 

 bone called opercular is comprised within a little more than 

 one-third of the length of this suture. 



As for the rest of the skeleton, no other difference exists 

 between that of the cayman and crocodile, but in total length. 

 The bones of the cayman are almost all a little broader in 

 proportion. 



The form of the bones of the gavial, also, have a prodigious 

 resemblance to those of the crocodile, only that the spinous 

 apophyses of the vertebrae are more squared. M. Cuvier 

 considers the normal number of vertebrae for all the living cro- 

 codiles of each sub-genus to be, seven cervical, twelve dorsal, 

 five lumbar, two sacral, and forty-two caudal, in all sixty- 

 eight. 



We now come to the fossil remains of this remarkable genus 

 of reptiles. 



The Fossil Crocodiles appear to be by no means of rare 

 occurrence in the ancient secondary strata ; and what is re- 

 markable is, that, though they all belong to species different 

 from each other, yet they are almost all referable to the sub- 

 genus with elongated muzzle, namely, the Gavials. 



We shall first notice an account of two fossils, discovered in 

 this country many years ago, though it is doubtful whether 

 they are really referable to this genus. The account of one 

 was published in 1718, by Dr. William Stukely; and the 

 other in 1758, by Messrs. Wooler and Chapman. 



