304 THEROMORPHA CHAP. 



them from Amphibia, without the intervention of Keptiles, 

 are as gratuitous as they have proved futile), and the Thero- 

 inorpha undoubtedly comprise creatures which of all animals 

 approach nearest to Mammals, and coincide with them in most 

 important features. But we have not yet found a single 

 Theromorph which can claim to be a direct ancestor of 

 Mammals. Since the latter occur already in the Trias, we have 

 to look for their reptilian forefathers at least in the Lower 

 Permian, and this naturally excludes all the known forms. The 

 filling up of this gap is but a question of time. 



The ancestry of the Theromorpha themselves is also 

 shrouded in mystery. Attempts have been made to connect 

 them with the Permian Protorosaurus, Palaeoliatteria, and Eryops. 

 On the other hand, some retain various Stegocephalous reminis- 

 cences (e.g. the roofed-in condition of the skull by membrane- 

 bones, amongst which, besides others, supratemporals and post- 

 orbitals can be recognised ; occurrence of cleithra in Pareia- 

 saurus ; distinct epiotic bones in Elginia). Although they 

 have died out as a group, they have perhaps given rise to 

 several side-branches, one of which (leaving aside the question of 

 Mammalian origin) seems to have flourished as the Dinosauria. 



We divide the Theromorpha into four orders, which are, how- 

 ever, liable to run into each other, and it is reasonably to be 

 hoped that many forms may be discovered which w r ill connect 

 not only these provisional orders with each other, but also with 

 other sub-classes. 



Order I. PAREIASAURI. 



Cranium completely roofed in by membrane-bones. The only 

 foramina are the nostrils, orbits, and the interparietal foramen. 

 The teeth are comparatively small, and stand in even series in 

 both jaws. 



Pareiasaurus, several species from the Karroo sandstone of 

 South Africa. P. baini was an extremely clumsy brute, of most 

 uncouth appearance, standing between 2 and 3 feet high, and 

 measuring with the short tail nearly 8 feet in length. The 

 skull is very massive, 18 inches long and slightly broader, 

 with a rugose, deeply pitted surface. The teeth are thickly 

 enamelled, serrated at the margin, with many pointed cusps ; those 



