i84 



THE OSTEOLOGY OF THE REPTH^ES 



centrale is usually retained in later reptiles, but the fifth tarsale is 

 absent in all reptiles since Triassic times, and a free centrale 

 is absent in all living reptiles, though present in most mammals. 



Fig. 151. Limbs: A, Trematops (Temnospondyli). One half natural size. B, Eosauravus 

 (Cotylosauria). About twice natural size. 



Fig. 152. Ophiacodon (Theroniorpha): right hind leg, from mounted skeleton. A little 

 less than one third natural size, a, astragalus; c, calcaneum. 



