BY C. W. DE VIS. 241 



only representative of a predeltoid ridge is a low prominence just 

 proximad of the middle of the long oblique margin joining the ends 

 of the two ridges. The breadth of the delto-pectoral surface is 

 15 mm. against 12*5 in platyrhinus, wherein again we recognise 

 an intermediate character. The triceps ridge on the anconal 

 aspect of the shaft is still less developed than in platyrhinus. 

 The absence of the supinator ridge and of the condyles precludes 

 further comparison, but perhaps enough has been said to render it 

 unnecessary. It may already appear that the bone, so far from 

 representing P. platyrhinus, has several characters which suggest 

 that, on the whole, P. mitchelli was less specialised than are the 

 living species of which it was probably the common source. 



Of the femur the length and the least transverse diameter are 

 respectively 168 and 17*5 mm., in P. platyrhinus they are 163 and 

 14-5, in P. latifrons 141 and 17 ; platyrhinus it would seem has 

 retained length and lost thickness, latifrons has lost length and 

 retained thickness. The breadth of the distal end (39 mm.), the 

 transverse diameter of the head (36*5), and its antero-posterior 

 diameter (26) are all greater than in either of the continental 

 species living. As in the humerus, so in the femur, the head 

 descends considerably lower and overhangs the shaft to a greater 

 extent than in existing forms. The lesser trochanter is relatively 

 larger in all its dimensions ; the rough-surfaced excavation in 

 front of its distal extension is much broader and deeper but has no 

 sunken pit at its proximal end ; the subtrochanterian ridge is more 

 exactly reproduced in platyrhinus than in latifrons. Between the 

 summits of the two trochanters the distance is 47-5 mm. against 

 44 in living species, consequently the neck is proportionately 

 broader. The inner condyle is 36 mm. in its antero-posterior 

 dimension, that of platyrhinus being ljut 31, and its superiority in 

 height over the outer condyle is, therefore, more conspicuous ; the 

 outer condyle is more distinctly grooved off from a rather broader 

 ectepicondyle ; the intercondylar notch is wider, the anterior limit 

 of its surface better defined, its whole surface comparatively 

 smooth ; a convexity of the surface near its posterior end forms a 

 low transverse bar between the condyles. Of the deep pit seen in 



