Cope.] 4^^ [Nov. 15, 



In the Proceedings of this 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 Prototlieria we have the 

 corresponding cartilage bone, the episternum. This element is present 

 in the Permian order of the Cotylosauria, which is nearly related to the 

 Pelycosauria." The examination of the sternal region in Pariotichus 

 has led me to the conclusion that the episternum and interclavicle are 

 present and fused together in that genus, and also to the belief that the 

 episternum is present in the genus Procolophon. The structure is gen- 

 erally similar in the two genera, and I think that Seeley is in error in 

 determining the element in question in Procalophon as the inter- 

 clavicle only.* Gegenbaur pointed out in his Comparative Anatomy the 

 different, i. e., membranous origin of the interclavicle of the Lacertilia, 

 but he included it with the episternum under the same name. The 

 true episternum is not present in the Lacertilia. It is present in the 

 Sauropterygia and Testudinata and probably in all the orders with one 

 postorbital bar, or Synaptosauria, while it is wanting in most or all of 

 the Archosaurian series, and in the Squamata. Whether the element I 

 have referred to in the genus Naosaurus as interclavicle, is that element 

 or the episternum, must remain uncertain until I can see it in place. Its 

 edges are thin, as in the interclavicle of the Lacertilia. Of course the 

 reptilian order which is in the line of ancestry of the Mammalia will 

 have an episternum, and not an interclavicle only. The Stegocephalia 

 among Batrachia possess an episternum, with, perhaps, an adherent 

 interclavicular layer as in the Testudniata. 



Seeley describes four sacral vertebrae in Pariasaurus. In Empedias 

 there are but two. The pelvis is without obturator foramen. The humerus 

 has an entepicondylar foramen. The tarsal and carpal elements are 

 incompletely known. 



There are palatine teeth in Empedias and Pariasaurus, but none in 

 Elglnia. 



The inferior surface of the cranium is known in Elginia, Pariasaurus, 

 Empedias and Pariolichus, and has been described as to the first three 

 genera by Newton, Seeley and myself. Pariotichus displays generally 

 similar characters. There is a pair of posterior nares, and a pair of Z3'go- 

 matic foramina, but there is no palatine foramen. The palatine elements 

 meet on the middle line, but gape behind. The vomers (prepalatines) are 

 distinct, and are well developed anterior to the palatines. The ectoptery- 

 goid is large and has a prominent posterior border. I have stated that in 

 Empedias there are teeth on the vomer. Better preserved specimens of 

 Pariotichus show that the teeth are really borne on the edges of the pala- 

 tines, which are appressed on the median line in the former genus. Simi- 

 lar palatine teeth are present in Pariasaurus, but are wanting in Elginia. 

 Teeth are also present on the posterior edge of the ectoptergoids in 



* Philos. Tramac. Royal Society, 1889, p. 275, Plate ix, Fig. 0. 



