194 SHUFELDT. 



unciform, magnum, trapezoid, trapezium, and scaphoid. Scaphoid is a 

 small compressed bone, but is larger than pisifomi; it has but a single 

 articular facet covering its entire mesial aspect that articulates with a 

 similar facet on semilunar. It is connected with the trapezium by liga- 

 ment only.-^ 



Trapezium of the distal row is only exceeded in size by the unciform. 

 It is of an irregular cuboidal shape, with articular facets for the proxmial 

 end of poUex metacarpal, trapezoid, and lunar. Above it, attached by 

 ligament only, we find the scaphoid, while mesially it presents a small facet 

 to the proximal end of index metacarpus. 



Having very nearly the same form and size, either being parallelepipedal 

 with respect to the former, the trapezoid and os magnum articulate with 

 each other and both with semilunar. Trapezoid also articulates with the 

 metacarpus of index digit, as os magnimi does with the same bone of the 

 middle finger. 



Unciform is a cube of irregular shape, the last carpal in the distal 

 row on the ulnar side, that articulates with lunar, cuneifomi, and the 

 metacarpus of minimus digit, and the inner side of the base of the meta- 

 carpus of the fourth phalanx. Its palmar process is but feebly developed. 



The manus of Cynoceplialus is large in proportion to the size of the 

 animal, and exliibits in its skeletal morphology the chief uses to which 

 • it is put, that is, being fitted to serve the purposes of climbing rather 

 than of prehension. It is especially long and rather narrow, being 

 armed distally with very efficient and f)owerfully hooked claws. It is a 

 pentadactyl member with a short pollex and four elongated digits. All 

 the phalanges composing these digits present the usual characters seen 

 among ordinary small mammals. Their shafts are very nearly straight 

 and quite cylindrical, while their distal extremities, or heads, support the 

 usual double trochlese for articulation with the jjhalanx next beyond 

 them in each instance. The base of each of these long bones is larger 

 than its head and also presents an artiettlar facet, which is oval and 

 concave to receive the head of the phalanx next behind it. The ungual, 

 or distal, joints are entirely different and will be described further on. 

 The metacarpus consists of five bones; distally they articulate with the 

 five proximal phalanges of the digits and at their other ends with the 

 carpus in a manner already pointed out. Pollex metaearf)al is very con- 

 siderably shorter than any of the others ; index and minimus metacarpals 



^ In describing this bone as tlie scaphoid, the fact is known to me that among 

 rodents there are many wherein the scaphoid and lunar unite to form a single 

 bone; and further that a special ossicle, which has been described as occurring 

 on the radical side of the wrist, is of very considerable size in Castw. It has 

 also been said that in the beaver the scaphoid and lunar fuse to form one bone. 

 Notwithstanding these statements it is contended here that the scaphoid is 

 present in Cynoceplialus^ though embryology may disprove it, and two centers of 

 ossification may be sho^vn to exist in the bone here described as semilunar. 



