854 prop, owen on EVIDENCES OF THERIODONTS IN PERMIAN 



This fossil, however, is the upper (proximal) portion of a reptilian 

 humerus, and most probably of the same species, if not bone, as 

 that on which the genus Brithopus is founded. Figured upside 

 down, as in Kutorga's plate ii., the articular head of the humerus, 

 (a, b in Cut, fig. 2) is made the " trochlea ; " the entotuberosity 

 (ib. c) becomes the " condylus internus;" the ectotuberosity is the 

 "condylus externus;" the delto-pectoral plate (ib. b x , b') is the 

 " supinator ridge" ("der iiber diesem Condylus stehende kamm"); 

 while the groove at the inner part of the fractured shaft, rightly 

 referred to as evidence of a " foramen condyloideum internum," is 

 the upper (proximal) commencement of that canal, which is shown 

 in its entirety and with its lower (distal) outlet in what I hold to 

 be the distal portion (Kutorga's pi. i.) of the humerus of the same 

 species or individual (Cut, fig. 1). 



The humerus of Ortliopus being reversed in position, as in Cut, 

 fig. 2, and being juxtaposed to fig. 1 (Brithopus), the characters 

 of the reptilian humerus, under theriodontal modifications, come 

 out unequivocally ; and the proportions are nearer those of the per- 

 forated humerus of Galesaurus and Dicynodon than of Cynodraco. 



The proximal articular convexity, or head, of the bone (Cut, 

 fig. 2, a) is a narrow semi-ellipse, its long axis transverse to that of 

 the shaft, its curved border being due to the usual production of 

 this articular surface backward, or anconad, in Reptiles. The ento- 

 tuberosity, c, is more definitely marked than in Cynodraco. The 

 ectotuberosity, 6, is represented by the angle formed by the out- 

 standing of the delto-pectoral crest as it descends from the axial line 

 of the head of the humerus to b'. The outer border of this large 

 and characteristic crest forms a low angle about halfway down 

 at b + ; then forms a second (almost right) angle at b', where it 

 returns to subside on the shaft of the humerus. The forward 

 (thenal) bend of the crest is not so marked as in Dicynodon ; it 

 does not exceed that shown in the humerus of Cynochampsa and 

 Cynodraco. The shaft of the humerus between the delto-pectoral 

 and supinator crests is as short and as contracted, compared with the 

 proximal and distal expansions of the bone, as in Cynodraco (loc. 

 cit. pi. xi. figs. 6, 7). The reptilian character of the distal portion 

 of the Brithopus bone (Cut, fig. 1) is shown by the shallow ill- 

 defined olecranal depression, by the absence of the definite trochlear 

 character of the distal articulation for the ulna, and by the presence 

 of the ectocondylar perforation, m. 



There is thus satisfactory evidence of an extinct reptile in the 

 Permian deposits of the Ural, with a humerus snowing the 

 same mammalian entepicondylar perforation as in certain extinct 

 reptiles of the Karoo series of South Africa, and with other modifi- 

 cations in which it more nearly resembles the Theriodont species of 

 those deposits. 



Brithopus prisms, Kutorga, as represented by the plaster cast, 

 is superseded by Eurosaurus uralensis, H. v. Meyer ; and I next 

 proceed to give the results of investigation of the ground of this 

 supercession and synonymy in the printed label of the dealer Krantz. 



