Class REPTILIA 



Order COTYLOSAURIA 



Cope, American Naturalist, 334, 1880. 



Primitive, crawling, or subambulatory, terrestrial reptiles, of 

 small to rather large size, with large head, short or no neck, heavy, 

 thickset body, and a moderately long or short tail, the skin either 

 bare or with bony ossicles; slender ventral ribs rarely present. 

 Skull stegocrotaphic, with all or nearly all dermal bones character- 

 istic of the Stegocephala; lachrymal (postnarial, adlachr)anal) 

 extending to the nares; septomaxillary usually if not always 

 present; postorbital always distinct; dermoccipital always, and 

 tabulare and supratemporal usually, present; a parietal foramen, 

 sometimes very large; paroccipital (opisthotic) separate; stapes large; 

 pterygoids articulating with vomers; transpalatine not yet demon- 

 strated ; teeth thecodont or acrodont, inserted on premaxillae, max- 

 illae, vomers, palatines, pterygoids, dentaries, and sometimes the 

 splenials. Prearticular of mandibles separate; splenial entering 

 into mandibular symphysis; coronoid of moderate size. Verte- 

 brae notochordal, twenty- three to twenty-five (?) presacrals, and 

 one or two sacrals; intercentra always present. Ribs usually 

 double-headed, in front, at least, and expanded but not emarginate 

 posteriorly, sometimes single-headed or double-headed throughout, 

 attached to intercentral space and diapophysis; free ribs on base 

 of tail. Vestigial cleithrum sometimes present; clavicles large; 

 interclavicle expanded anteriorly, with a long stem; no ossified 

 sternum. Coracoid co-ossified with scapula; sutural division be- 

 tween coracoid and metacoracoid in glenoid fossa; a supraglenoid 

 canal always present. Pubis and ischium large, plate-like, with- 

 out pubofschiadic vacuity, but with an obturator foramen piercing 

 the pubes; iUum more or less dilated posteriorly above. Humerus 

 with broadly dilated extremities, in very divergent planes; an 

 entepicondylar foramen always present; no ectepicondylar fora- 



15 



