PRE-JURASSIC TETRAPODS. 171 



Class REPTILIA. 



It is now impossible to give any definition of the class Reptilia 

 which, whilst including all members of the gi'oup, will exclude 

 all other Tetrapods. The essential feature of a reptile is that it 

 can carry out the whole of its life-history on dry land, not pro- 

 ''ducing a gill-breathing larva, and that it is not a mammal or a 

 bird. Reptiles lay a shelled egg except in viviparous forms, in 

 which the egg is hatched before it is laid. 



Super-Order COTYLOSAURIA (Cope). 



Reptiles with a roofed skull and plate-like pelvis. The 

 members of this super-order are merely held together by these 

 primitive characters, the typical forms also by many other 

 common primitive reptilian characters lost by the advanced 

 members of this group. 



Order Seymouriamorpha, nov. 



CotylosaCurs with a skull resembling in nearly all known 

 details that of the Anthracosaui'idte. Otic notches small, quad- 

 rate inclined backward. Tabulars and dermo-supraoccipitals 

 on the skull roof, but with occipital flanges. Pro-otic reaching 

 the skull roof. Inner ear widely open to the cranial cavity in 

 the latei'al wall of the cranium. Vertebrse with very heavy and 

 expanded arches and very large intercentra. 



Limbs very primitive, like those of the Rhachitomous amphi- 

 bian Eryops in many features. 



Seymouria Broili. Artinskian, Texas. 



Order Diadectomorpha, nov. 



Cotylosaurs with exaggerated laterally placed otic notches and 

 a vertically placed quadrate. 



Super- Family Diadectid^ Cope. 



Diadectomorphs with a long low brain-cavity. Tabulars and 

 interparietal turned down onto the occipital surface, closed post- 

 temporal vacuities. Inner ear widely open to cranial cavity. 

 Vertebrae with heavy neural arches. Limbs primitive. 



Dladectes Cope. Artinskian, Texas. 



Diadectoides Case. ,, ,, 



Xothodon Marsh. '?U. Coal Measures, New Mexico. 



Aniniasaurus Williston. ,, ,, ,, 



? Desmatodon Case. ,, ,, Pennsylvania. 



Diasparactas Case. ,, ,, New Mexico. 



Chilonyx Cope. Artinskian, Texas. 



"^ Stephanospoiidylus Geinitz; & Deich. M. Rothliegentle, 



(Saxony. 

 12* 



