RHYNCHIPPUS 93 



The carpus is preserved in toto and is decidedly weak 

 for an animal of this size, though no more so than is the 

 case of Xesodon and Adinotherium, with which forms the 

 arrangement of the bones agrees in almost every detail. 

 The scaphoid has a broad facet on the upper side for the 

 radius, on the ulna side a narrow band-like facet for the 

 luna, and distally facets for the trapezoid and the magnum, 

 none for the trapezium. The luna is a larger bone with a 

 broad radial facet on the upper side, a narrow facet for the 

 scaphoid on the radial side, a larger one for the pyramidal 

 on the ulnal side, and two broad facets for the magnum 

 and unciform on the lower side. The pyramidal is a low, 

 flattened bone, with a cup-like facet for the ulna on the 

 upper surface, an elongated flat facet for the pisiform on 

 the palmar surface, and below a broad facet occupying the 

 entire lower side for the unciform. The pisiform is shaped 

 like a tiny calcaneum, and, beside the facet for the pyra- 

 midal, has a broad contact on the styliform process of the 

 ulna. The trapezium is a flattened nodular bone, resting 

 against the side of the upper end of Mc. II, for which it has 

 a flattened contact surface, but it does not properly artic- 

 ulate with any of the carpals. The trapezoid is a small 

 bone, cuboidal in shape, with the proximal facet for the 

 scaphoid rounded, and with a narrow facet for the sup- 

 port of Mc. II on the distal end. The magnum is a larger 

 bone, articulating proximally with the scaphoid and luna, 

 on the ulnal side with the unciform and distally supporting 

 Mc. III. The unciform is the largest of the carpal bones, 

 articulates proximally on the luna and pyramidal, on the 

 radial side with the magnum, and distally carries Mc. IV, 

 while on the ulnal side there is a facet for the modular ves- 

 tige of Mc. Y. 



The metacarpals are longer than those of Adinotherium, 

 and are much more closely pressed together, making a 

 narrower, firmer foot. Three metacarpals are present 

 (beside the modular vestige of Mc V.). Mc. II and Mc. IV 



