THE LIMBS l6l 



fossa, the horizontal position of the humerus in locomotion, and 

 the more turtle-like mode of progression. The digits in such animals 

 are never long, and the ungual phalanges are short and stout. 



At the distal extremity of the humerus (Figs. 131, 133), on the 

 preaxial and more or less ventral side, there is a more or less convex 

 surface, the radial condyle, or capit-ellum, for the articulation of the 

 radius. Contiguous with it on the postaxial side, but more distal and 

 dorsal, is the ulnar condyle or trochlea, for articulation of the ulna. 

 In aquatic reptiles {e. g., Fig. 158 c, d) both of these are simple 

 facets at the extremity of the humerus. The projection or process on 

 the radial or preaxial side, above the radial condyle (Figs. 129 A, 131), 

 in the short-limbed cotylosaurs and theromorphs as also the temno- 

 spondyl amphibians, sometimes turned more dorsad, is known as the 

 radial epicondyle, ectocondyle, ectepicondyle, or pre-epicondyle. In the 

 very stout-limbed cotylosaurs (Figs. 130, 133 sc.p.) and theromorphs 

 (Fig. 131), as also the stout-legged temnospondyls (Fig. 136), there is 

 a stout process on the radial side above the epicondyle. It is espe- 

 cially correlated with short digits and doubtless a more turtle-like 

 mode of progression. It may be known as the supracondylar process. 

 The distal expansion of the humerus on the ulnar or postaxial side is 

 commonly known as the entocondyle or entepicondyle, misleading 

 terms (Figs. 130, 131, 133 ewi.). 



Piercing the condylar expansions more or less obliquely (Fig. 



129 a) are very characteristic foramina in most reptiles. That on the 



ulnar side, the entepicondylar foramen {entep.J.),ior the passage of the 



median nerve, occurs in all Cotylosauria, Proganosauria, Theromor- 



pha, and most therapsids, and in not a few mammals. A similar 



foramen on the radial side, the ectepicondylar foramen (Fig. 129 a, 



ectep.f.), for the passage of the radial nerve, is characteristic of most 



Lacertilia, Chelonia, Choristodera, and Phytosauria. In some of 



these it is replaced by a groove, and the latter is present in the 



Mosasauria and young Plesiosauria. Both the ectepicondylar and 



entepicondylar foramina occur in some Theromorpha and Anomo- 



dontia, the Nothosauria, Rhynchoceph.s.h.a., Araeoscelis, Pleurosaurtis , 



etc. The Pterosauria, Dinosauria, Crocodilia, Ichthyosauria, and 



. * 

 Plesiosauria have no epicondylar foramina. 



The humeri of many known temnospondylous amphibians differ 



but Kttle from those of the Cotylosauria, save in the absence of the 



