289 FOSSIL REPTILES. 



and tortoises, and still more from salamanders. M. Cuvier would 

 also join with them the serpents of the family of anguis, for 

 their osteology, especially that of the head, greatly resembles 

 that of many lizards. 



As to the head, the principal characters of this family are as 

 follow : — 



The four common occipital bones form the ring which sur- 

 rounds the encephalon behind. The lateral occipital is not 

 divided into two portions, as in the tortoise. In front of the 

 occipitals are placed the sphenoid, underneath, and the os 

 petrosum laterally. The parietal covers the whole as a roof or 

 penthouse. 



The sphenoid is visible throughout its entire lower face. The 

 pterygoidean bones forming a simple continuation of the pala- 

 tines, are prolonged as far as the internal edge of the ossa tym- 

 pani, not touching the sphenoid, except on a lateral tuberosity 

 of that bone, and not uniting together. The sphenoid is pro- 

 longed in front, by a cartilaginous process, on which is raised 

 the interorbital partition, and in this last are seen many points 

 of ossification which belong to the ethmoid. The bone which 

 is analogous to the petrosum, and which is not concealed by 

 the tympanic box, extends externally, and forms between the 

 sphenoid, and the occipitals, all the hinder lateral paries of the 

 cranium. The lateral and anterior paries of the cranium, from 

 the OS petrosum to the interorbital partition, is membranous, 

 and contains only, on each side, a bone differently configurated 

 according to the species, and which represents the temporal 

 and orbital wings. 



An osseous stem arises from the upper edge of the ptery- 

 goid, where it is articulated into a fosset, as far as the lateral 

 edge of the parietal, where it attaches by a ligament. Some 

 anatomists have imagined that this bone was analogous to the 

 temporal wing, but it does not perform the functions of that 

 bone. Others have named it the tympanic bone, for which 

 there does not appear to be the slightest foundation. It cannot 



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