256 FOSSIL REPTILES. 



Behind the maxillaries and the posterior frontals, on the 

 two sides of the vomer are the palatines, surrounded behind 

 and externally by the pterygoidea, which last extend along the 

 external edge of the palatines as far as the maxillaries. The 

 rest of these pterygoidean bones covers the lower face of the 

 cranium, between the two ossa tympani and the two temporal 

 wings, leaving visible behind only a small triangular portion of 

 the body of the sphenoid. The palatines have only their 

 upper part, and want the curved part which prolongs the floor 

 of the palate behind the maxillaries. The lachrymal bone is 

 not discoverable in the tortoises, no more than in the phocae 

 and dolphins. 



The olfactory and optic nerves come forth through cartila- 

 ginous partitions of the cranium, and have no particular fora- 

 men in the skeleton. The same appears to hold good for the 

 third and fourth pair. The sixth passes through a small canal 

 of the body of the sphenoid. The fifth pair has a large fora- 

 men between the os petrosum and the temporal wing, divided 

 into two at the exterior. At the external edge of the palatine 

 there is a foramen analogous to the pterygo-palatine. 



Internally, the cerebral cavity is more high than wide. 

 The bottom is very even. But in front, in the sphenoid, is a 

 deep fosset for the pituitary gland, a sort of sella turcica. 

 From the sides of this part originate the cartilaginous parti- 

 tions, which, joining the ante-cerebral partition of the frontal, 

 close the cavity of the cranium in front, support all the anterior 

 portion of the encephalon, hold the place of the lamina cri- 

 brosa, of the orbital wings, and of the greatest portion of the 

 temporal wings ; another considerable part of which is replaced 

 by the descending portions of the parietal, so that what re- 

 mains does not participate in the formation of the cerebral 

 case, except a little in front of the foramen of the fifth pair. 



There is no bony vestige of an anterior sphenoid any more 

 than in the crocodile. 



This description, taken from the Indian tortoise, is equally 



