OSSEOUS SYSTEM OF MAMMALIA. 307 



digit ; a ' magnum/ m, supporting that of tlie middle digit, and 

 an ' unciforme,' u, limited to the rudiment of iv. 



In the huge extinct congener of the Sloths (^Megatheriuni), the 

 fourth, IV, as well as the third and second digits are developed, 

 as in the Bradyjnis tridactylus, for the support of claws. There 

 is a metacarpal of the fifth digit, supporting stunted rudiments of 

 the first, 1, and second, 2, phalanges; the first digit is still repre- 

 sented by a like rudiment of its metacar2:)al, i. The carpal 

 ossicles include, as in Sloths, a ^ scapho-trapezium,' s, t, with a 

 well-marked ^ pisiforme,' p, and a larger ^ unciforme,' u. In the 

 HycEna the fifth digit, v, is functionally developed : the first, i, 

 retains the rudimental state. The scaphoid and lunare, s, /, have 

 here coalesced : the trapezium, t, is distinct, but very small : the 

 unciforme supports, as usual, the metacarpals of the fourth, iv, 

 and fifth, v, digits. In the Spider-Monkey {Ateles), the meta- 

 carpal representative of the first digit, i, is longer : the scaphoid, 

 s, is distinct, and the ' intermediilm,' /, is a dismemberment 

 thereof, answering to e, fig. 173, Yol. I. 



In the Orang the carpus also has the dismembered sca- 

 phoid, s, or ' intermedium,' /. The inner digit, i, is short and 

 feeble, but with the usual mammalian number of two pha- 

 langes. In the hand of Man, this digit, which is the last to 

 be completed in that class, attains its highest functional deve- 

 lopement : it is articulated in such a way and at such an angle 

 as to be opposable to any of the joints of any of the other digits. 

 Of these the third, ill, which is the most constant in the class, is 

 the longest. The carpus con- 

 sists of eight bones in two 

 rows ; the first including the 

 undivided * scaphoides,' s, ' lu- 

 nare,' /, ' cuneiforme,' c, '• pisi- 

 forme,'/? ; the second including 

 ' trapezium,' t, ' trapezoides,' 

 d, * magnum,' ???, ^ unciforme,' 



U. These names, SUG:2:ested Pelv-lc arch and appendage, i}ateHrtJy//6(ue«(ts. 



. LXV. 



by the shapes and proportions 



of the carpal bones in the human skeleton, become arbitrary signs 



of their homoloo'ues in lower animals. 



The appendage of the pelvic arch may be wholly Avanting, as 

 in Sirenia and most Cetacea, or represented by a two-jointed ray, 

 as in the Right Whale, fig. 192, and fig. 159, 65, 66 ; articulated to 

 two elements, 63 and 64, of the pelvic arch, which, as in Fishes^ 

 are loosely suspended in the flesh. 



