212 ME. ST. a. MIVART ON THE SKELETON OP THE PRIMATES. 



of Man. The external proximal process, or tuberosity (PI. XLIII. figs. 52 & 5-3 a) 

 is smaller in the Orang than in the higher forms; and in this the fifth metatarsal 

 differs less from the fifth metacarpal than in them. 



As in the Gorilla, the tibial articular surface is less antero-posteriorly extended than 

 in Man. 



The proximal surface of this metatarsal is very much more concave and less convex; 

 than is tlae corresponding surface of the fifth metacarpal. 



Digits. 



The proximal phalanges of the four outer digits are very much curved', with the con- 

 cavity downwards (PI. XLI. fig. 12), much more so than are their homotypes of the 

 manus. They ai-e also narrower transversely, less flattened below and rather shorter, 

 than are the latter. In these last three points, however, they differ less from their 

 homotypes than do the same proximal phalanges of Troglodytes from their serial homo- 

 logues, and of course very much less than do those of Man. The proximal phalanx of 

 tlic hallux is much shorter than is the homotypal segment in the Orang^, a circumstance 

 in which it differs from all the higher forms. The second phalanges of the four outer 

 digits are shorter and naiTower than are theii- homotypes ; but again the difference is 

 less than in Troglodytes, and greatly less than in Man. 



The second 2:)halanx of the hallux is often absent', but when present is much shorter 

 than is its homotype of the poUcx'', in which respect the Orang again differs from the 

 superior forms. The third or distal phalanges scarcely diff'er in length from those of 

 the manus, and at the most they are but a trifle shorter, thus agreeing with Troglodytes 

 and differing much from Man. 



The hallux with its metatarsal, when compared in length with the spine, I have found 

 to be only as about 13-6 to 100, instead of from about 17 or 18 to 100 as in Man and 

 Troglodytes ; compared with the length of the entire pes, it barely exceeds a quarter, 

 instead of approaching one-half as in them. The index with its metatarsal, as compared 

 with the length of the spine, is very much longer than in the higher forms, as also is the 

 third digit. Without their metatarsals, these digits, when compared with the length of 

 the entire pes, are not so very much longer than in the Chimpanzee (39 and 42 to 100, 

 instead of 32 and 34), but they of course greatly exceed those of Man. 



The proportion borne by the whole hallux to the whole poUex is strikingly different 



- ' Professor Huxley, ' Medical Times,' 18C4, vol. i. p. 565. 



' See Luoae, he. cit. plate iii. figs. 5 & 9. ' See Lucae. he. clt. plate iii. tigs. 5 i 9. 



' Camper found this to be the case in seven out of eight Orangs (CEuvres, torn. i. p. 54). Two phalanges, 

 however, are recorded in two cases by Professor Owen, Trans. Zool. Soc. vol. i. p. 367. W. Vrolik, he. cU. 

 pp. 15 & 10, says, " One or two phalanges are present," and appears inclined to think that the distal one may 

 disappear with age. De Blainville, loc. cit. p. 32, records five cases, in each of which the hallux had two 

 phalanges. 



