529 



[Cope. 



o.a. The shaft interrupted by a prominent diagonal ridge. 

 No. 4. Epicondyles and ridges enormous Sp. 1. 



AAA. No supracondylar fossa ; condyles as in A A. 



No. 5. Form more slender Sp. 3. 



No. 6. Form more robust Sp. 1. 



The above humeri represent three, and perhaps four genera, which have 

 been probably already named from crania or vertebra? in the preceding- 

 pages. No. 1 has been already identified as belonging to the Clepsydrops 

 natalis. Nos. 2 and 3 are generally similar to the type referred by Meyer 

 to the Eurosaurus of Fischer, which had been previously described as 

 Mammalian by Kutorga ; but the epicondyles are more largely developed. 

 Humerus of form No. 4 is very remarkable, resembling in some degree 

 that of a mole, being exceedingly robust, and having the muscular inser- 

 tions enormously developed. It doubtless belonged to a fossorial animal, 

 possessing great power in the anterior limbs. If we search for vertebrae 

 presenting features corresponding to such a mode of life, we sieze at once 

 on those of the genus Empedodes. Here the elevated roof-like character 

 of the zygapophyses and the connecting platform suggest protection against 

 superincumbent weight, while additional strength is obtained by the 

 hyposphen articulation below them. The short wide neural spine is high- 

 ly appropriate also to subterranean habits. It is also probable that the 

 animals possessing the humeri, from No. 2 to No. 6 inclusive, were all 

 more or less fossorial. Humeri Nos. 5 and 6 have the characters of Nos. 

 2 and 3, but the supracondylar bridge is wanting, and the internal epicon- 

 dyle not quite so much expanded. 



The division Pelycosauria is established primarily on the genera Clepsy- 

 drops and Dimetrodon, but their cranial structure renders it highly proba- 

 ble that Ectocynodon, Pariotichus and Bolosaurus belong to it. It is also 

 probable that the genera Empedodes, Embolophorus and others determined 

 from vertebra? belong to it, as the latter are frequently accompanied by 

 pelvic bones of the type of that of Dimetrodon. All the genera known 

 from teeth and crania, are of carnivorous habit, excepting Bolosaurus and 

 Diadectes ; they may be referred to a single family on this account, which 

 I call the Clepsydropidm. Bolosaurus will form the type of another fam- 

 ily characterized by the transverse position of the crowns of the teeth, un- 

 der the name of Bolosauridce. Prof. Owen has named a group of Triassic 

 and Permian reptiles the Theriodonta, characterized by the mammal-like 

 differentiation of the incisor and canine teeth. The animals thus referred 

 by Prof. Owen probably enter my suborder of Pelycosauria, although the 

 structure of their pelvis remains to be ascertained. If so, they correspond 

 with my Clepsydropidce, since Prof. Owen does not include herbivorous 

 forms in his division. As it is plain that the herbivorous and carnivorous 

 types belong to the same order, and probably suborder, it becomes neces- 

 sary to subordinate the term Theriodonta to that of Pelycosauria. To 

 another division of reptiles from the South African Trias typified by the 



PROC. AMER. PHILOS. SOC. XVII. 101. 3x. 



