Geology and Paleontology. 



GEOLOGY AND PALEONTOLOGY. 



The Paleozoic Reptilian Order Cotylosauria.— A paper was 

 read before the American Philosophical Society, November 15, 1895, 1 

 by Prof. E. D. Cope, on the reptilian order Cotylosauria. The fol- 

 lowing is an abstract of the characters of the order. 



Quadrate bone united by suture with the adjacent elements. Tem- 

 poral fossa overroofed by the following elements : Postfrontal, post- 

 orbital, jugal, supramastoid, supratemporal, quadratojugal. Tabular 

 bone present. Vertebra; amphicoelous ; ribs one headed. Episternum 

 present. Pelvis without obturator foramen. 



This order is of great importance to the phylogeny of the amniote 

 Vertebrata. The structure of the temporal roof is essentially that of 

 the Stegocephalous Batrachia, while the various postorbital bars of the 

 amniote Vertebrata are explained by reference to the same part of its 



The palatal elements in this order are more or less in contact on the 

 middle line, and the pterygoids diverge abruptly from this point, and 

 return to the quadrate. The occipital condyle is single, and does not 

 include exoccipital elements (unknown in Elginia). 



Intercentra are present in Pariasauridae, Diadectidte and Parioti- 

 chidse, and they are wanting in Elginiidte. The hyposphen-hypan- 

 terum articulation is present in the Diadectidse, but is wanting in the 

 Elginiidse and Pariasauridse. 



The scapular arch is best known in Pariotichidse, Pariasauridse 2 and 

 Diadectidse. In the two former there is a T-shaped episternum, over 

 which are applied the median extremities of the clavicles ; and there 

 are well-developed coracoid and praecoracoid. In Diadectidse 3 (prob- 

 ably genus Empedias) the episternum is articulated by suture with the 

 clavicles. 



In the Proceedings of the American Philosophical Society, 1892, p. 

 279, in a paper on " The Phylogeny of the Vertebrata," I wrote as 

 follows : " Moreover, the Pelycosauria and the Procolophonina have 

 the interclavicle, which is an element of membranous origin, while in 

 the Prototheria we have the corresponding cartilage bone, the epister- 

 num. This element is present in the Permian order of the Cotylo- 



1 See Proceedings Amer. Philos. Soc., Vol. XXXIV, 1896, p. 436. 



2 Seeley, Philos. Trans. Roy. Soc. London, 1888, p. 89; 1892, p. 334. 



3 Cope, Proceeds. Amer. Philos. Soc., 1883, p. 635. 



