THE SKULL OF REPTILES 



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homologous with the mammaKan alisphenoid, though usually so 

 called. Imperfectly known in the early reptiles, they have been recog- 

 nized in the Temnospondyli, Cotylosauria, and Theromorpha, ar- 

 ticulating as in the Crocodilia (Fig. 69) below with the basisphenoid, 



Fig. II. A, B, C, D, Dimetrodon. Pelycosaur skull: occipital complex: A, from below; 

 B, the same from above; C, obliquely from behind; D, the same from in front. Temno- ' 

 spondyl skulls: E, Eryops, section through parasphenoidal rostrum, near front part of 

 orbit; F, Eryops, section through parasphenoidal rostrum near base; G, Cacops, section 

 through parasphenoidal rostrum at middle of orbit. 



above with the parietal, back of the optic foramen, whence the name 

 postoptics given to them by Cope. Between them and the prootics 

 is the foramen for the fifth nerve. They form the lateral brain-case 

 in the Crocodilia, but are absent in the Chelonia and snakes. In the 

 lizards they are imperfectly ossified, and are usually lost in prepared 

 specimens. They are present in the Rhynchocephalia and most 

 other reptiles. 



