homologous with the mammalian alisphenoid, though usually so called. Imperfectly known in the early reptiles, they have been recognized in the Temnospondyli, Cotylosauria, and Theromorpha, articulating as in the Crocodilia (Fig. 69) below with the basisphenoid, above with the parietal, back of the optic foramen, whence the name postoptics given to them by Cope. Between them and the proötics 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.
Fig. 11. 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. Temnospondyl 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.
