HISTORICAL REVIEW OF THE PELYCOSAURIA. 9 



genus Pantybis. In the same paper the validity of the suborder Cotylosauria 

 was questioned, as it already appeared that the double articular condyles 

 were the result of the accidental loss of the basioccipital. Cope says, p. 448 : 

 " I am still incliued to question whether the extraordinary characters of the cranio- 

 vertebral articulation which I have described, justify the separation of the Diadectidce 

 as a third suborder of the Theromorpha, which I have called the Cotylosauria, or 

 whether they are not due to the loss of a loosely articulated basioccipital bone." 



In 1883 (56) Cope described a new species oi Pariotichus, P. megalops^ 

 and erected a new family Parioti chides, to contain Pariotichus, Pantyltis, and 

 probably Edocynodon. In this same paper the Diadedidce were shown to 

 possess a basioccipital bone with a single occipital condyle, and the sub- 

 order Cotylosauria is not mentioned ; it had disappeared, as it was founded 

 on the supposed double occipital condyle; all Permian reptiles of the United 

 States were thus placed by Cope at that time in the Pelycosauria. 



In 1884 (60) appeared Cope's "Fifth Contribution to the History of the 

 Vertebrata of the Permian Formation"; the substance of the paper was also 

 published in the Proceedings of the American Association for the Advance- 

 ment of Science (62) in 1885. In these papers there is a further discussion 

 of the relationship of the Pelycosauria to the mammals. 



" I. The relations and number of the bones of the posterior foot are those of the 

 Mammalia much more than those of the Reptilia. 



"2. The relations of the astragalus and calcaneum to each other are as in the 

 Monotreme Platypus anatinus. 



"3. The articulation of the fibula with both calcaneum and astragalus is as in 

 the Monotreme order of mammals. 



" 4. The separate articulation of the anterior part of the astragalus with the 

 tibia is as in the same order. 



" 5. The presence of a facet for an articulation of a spur is as in the same order. 



" 6. The posterior-exterior direction of the digits is as in the known species of 

 Monotremata. 



"Thus the characters of the posterior foot of the Pelycosauria confirm the evi- 

 dences of Monotreme affinity observed by Prof Owen and myself in the bones of the 

 legs, especially of the anterior leg. It remains a fact that with this resemblance in the 

 leg there is a general adherence to the reptilian type in the structure of the skull." 



In 1885 (64) Cope published a paper in the American Naturalist in 

 which he derived all the reptiles with the possible exception of the Ichthy- 

 osaurs from the Theromorpha. 



In 1886 (70) appeared his "Systematic Catalogue of the Species of 

 Vertebrata found in the beds of the Permian Epoch of North America." 

 The larger divisions stand as follows: 



Order Theromorpha. 



Suborder Pelycosauria. 



Families Clepsydropidce , Pariotichidce , Bolosauridte, Diadectidce. 



