320 
MR. ST. GEORGE MIYART ON THE SKELETON OF THE PRIMATES. 
disappears * * * § (Plate XIV. fig. 3). In Simia it is sometimes as marked as in the Gorilla; 
sometimes, however, it can hardly be said to exist at all. 
In Hylobates there is no trace of any concavity, but a strongly convex and rounded 
tubercle receives the concave articular surface of the base of the metacarpal of the 
pollex f . 
In the lower Simiidse the concavity is again sometimes present, though it is always 
very slight, and occasionally in Semnopithecus there is no indication of it, though in 
Colobus I have found it decidedly present, but slight ; in Dr. Lucas’s specimen, however, 
it was absent J. 
In Ateles the trapezium is large in spite of the rudimentary condition of the pollex ; 
but there is no saddle, i. e. no concavity for the metacarpal §. 
In the other Cebidse the depression sometimes exists. I have observed a decided, 
though small saddle in Brachyurus and some specimens of Cebus ; in others I could 
detect no trace of such a structure, nor have I found such in the other genera of Cebidse 
I have been able to examine. 
In the Lemuroidea the concavity is very slight, though it may generally be detected. 
The trapezium is always so placed that the axis of the convexity of the saddle forms 
a marked angle with a line drawn across the articulations of the four outer metacarpal 
bones with the proximal row of carpals || (Plate XIV. figs. 6 & 7). 
In Man and the Gorilla this angle is very open, but in the Chimpanzee and some- 
times in lower Simiidee it is smaller, the trapezium being, as it were, somewhat more 
pressed inwards, at its radial end, towards the middle of the palm. It is never, however, 
so inclined inwards as is the axis of the cylinder of the entocuneiforme of the pes, 
though the resemblance is considerable in the Chimpanzee, which thus differs from the 
inferior forms, as well as from Man. 
In the American Anthropoidea the trapezium is well set out ; and this, no doubt, con- 
tributes to produce that very feeble opposition and palmad flexion of the pollex which 
have been noticed to exist in them. 
Trcipezoides . — This bone is generally pyramidal in shape, the apex being towards the 
palm. It is more pointed at its palmar end in the lower Simiidse than in Man, and still 
more so in Lemur. 
It is very small in Tarsius % but of ordinary relative size in Arctocebus and Perodic- 
ticus, in spite of the rudimentary condition of the index. 
* E. g. the mounted manus, No. 744, in the same collection. The absence of a saddle in this species is 
noticed by Professor Huxley : see * Medical Times',’ 1864, vol. i. p. 428. 
t Noticed by Dr. Lucae, loc. cit. p. 305, and Tab. 4. fig. 8. 
j Loc. tit. p. 311. 
§ Dr. Lttcae speaks of the convex articular surface which, in Ateles, is received into the concavity of the 
metacarpal (loc. cit. p. 311). 
|| The “ digital angulation” of Professor Huxley. See ‘ Medical Times,’ vol. i. p. 177. 
If Burmeistek, loc. cit. Tab. 2. fig. 5, g. 
