218 TUE ANATOMY OF VERTEBRATED ANIMALa 



FN 



Fig. 77.— Longitudinal and vertical section of the hinder part of the skuli of a Crocodile; 

 £hi^ Eustachian tube : P N^ posterior nares ; P, pituitary fossa. 



2. All the bones of the skull (except the mandible, stapes, 

 and hyoid) are firmly united by sutures, which -persist through- 

 out life. 



3. There are large parotic processes. Both the upper and 

 the lower temporal arcades are completely ossified, and formed 

 by post-frontal, squamosal, jugal, and quadrato-jugal bones; 

 Bupra-temporal, lateral- temporal, and post-temporal fossae are 

 formed, as in the Lacertilia, though their relative sizes are 

 \rery diiferent. 



4. The maxillary and the palatine bones develop palatine 

 plates, which unite suturally in the middle line, and separate 

 the nasal passages from the cavity of the mouth, as in Main- 

 malia ; and in aU existing Crocodiles, but not in Teleosavrm 

 or Selodon, the pterygoids are also modified in the same way 

 (as in Mymercophaga among Mammals), so that the posterior 

 nares are situated very far back beneath the base of the skull. 



5. In consequence of the development of these palatine 

 plates of the maxillary and palatine bones, the two vomers 

 are, in most Crocodiles, invisible upon the under-surface of 

 the bony roof of the mouth. 



