362 PROF. OWEN ON EVIDENCES OP THERIODONTS IN PERMIAN 



' Descriptive Catalogue of the Osteological Series contained in tho 

 Museum of the Royal College of Surgeons,' it was first shown that 

 the " foramen condyloideum externum " was a character of a rep- 

 tilian humerus*. 



Professor Huxley was the first to figure the canal homologous with 

 Kutorga's " foramen condyloideum internum," under the term " supra- 

 con dyloid foramen or canal," in a humerus of a Dicynodon from the 

 Panchet rocks of India, and in the humerus of a Dicynodon from 

 the Karoo series of the Cape, in elucidation of which character he 

 remarks : — " A supracondyloid foramen occurs not unfrequently 

 among Lacertian Eeptiles, but not with the precise form and pro- 

 portions which it presents in these two humeri " f. 



The determination of the homology of the supracondyloid foramen 

 in the humerus of the Dicynodonts and Theriodonts is given in the 

 i Catalogue of S.- African Reptilia' +, and in the paper on Cynodraco §. 

 It illustrates the mutual affinity of the two extinct groups, and their 

 common possession of a mammalian structure. A like determination 

 of the homology of Kutorga's " foramen condyloideum externum " 

 converts into certainty the suspicion expressed by Agassiz of the 

 reptilian nature of Brithopus and Orthopus. An ectepicondylar 

 foramen or canal has hitherto been seen only in the humeri of cold- 

 blooded vertebrates ; an " entepicondylar foramen or canal," charac- 

 teristic of many genera of Mammalia, is also characteristic of the 

 humerus in certain Reptilia, but has hitherto been found only 

 in extinct genera and species of Palaeozoic or Permian age. 



Thus is exemplified the value of close study and comparison of 

 small and seemingly insignificant foramina and other minute cha- 

 racters of fossil bones, the advantage of defining such characters, 

 their homologues being determined under distinct names, and the 

 in dispensability of such labour in all who would contribute to " the 

 progress of sound palaeontology" ||. 



Discussion. 



Professor Seeley could not realize Prof. Owen's new order. It 

 seemed to him to rest upon the collocation of specimens, for which 

 there seemed to be no sufficient evidence to justify the foundation 

 of a new order upon them. It seemed to be stretching a point a 

 very long way to refer all these isolated specimens to a new order 

 of which we know so little. The Bristol specimens of Palceosaurus 



* 4to, vol. i. p. 184, no. 943 (1853). 



t " On Vertebrate Fossils from the Panchet Rocks," &c. in ' Memoirs of the 

 Geological Survey in India,' 4to, 1865, p. 10, figs. 3 a, b. See, however, the 

 remarks in the Quart. Journ. Geol. Soc. vol. xxxii. p. 98. 



The figure and description of the left humerus of the Dicynodon Murrayi, 

 Huxley, in ' Quart. Journ. Geol. Soc' vol. xv. 1859, exemplify the difficulty 

 attending the investigation of fossils from the dark hard matrix of the Karoo 

 beds. 



\ Quarto, 1876, pp. 35, 43, 53 ; Nos. S. A. 59, S. A. 72, S. A. 88 ; pis. xxvii. 

 xli., xlii. 



§ Quart. Journ. Geol. Soc. vol. xxxii. (1876) p. 96, pi. xi. figs. 6-11. 



j| Quart. Journ. Geol. Soc. vol. xxvi. (1869) p. 32. 



