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 capitellum, 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 temnospondyl 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 especially 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 ent.).
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. f.), for the passage of the median nerve, occurs in all Cotylosauria, Proganosauria, Theromorpha, 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 Anomodontia, the Nothosauria, Rhynchocephalia, Araeoscelis, Pleurosaurus, etc. The Pterosauria, Dinosauria, Crocodilia, Ichthyosauria, and Plesiosauria have no epicondylar foramina.
The humeri of many known temnospondylous amphibians differ but little from those of the Cotylosauria, save in the absence of the
