MR, ST. GEORGE MIVART ON THE SKELETON OF THE PRIMATES. 
311 
It scarcely projects below the radial margin, and a fortiori not below the capitellum 
in the Gorilla, Hylobates, Hapale, Indris (Plate XII. fig. 6), and Lemur. 
Radius and Ulna. 
Both these bones are always distinct and separate in the Primates, and being approxi- 
mated at their extremities, diverge more or less from each other midway, the divergence 
being relatively most extreme in the Gorilla and Indris (Plate XII. fig. 7). 
Radius. 
The radius is absolutely longest in the Gorilla and Orang, but in the Chimpanzee and 
Siamang it is also longer absolutely than in Man. 
Its length, as compared with that of the spine, is greatest in Hylobates, being more 
than four-fifths of the length of the latter. It is more than three-fifths in the Orang and 
Ateles, half, or a little more, in Troglodytes and Tarsius. In the great bulk of the order 
it is between three-tenths and two-fifths (Man being about as 35 to 100) of the length 
of the spine. It is a little less in the Nyctipithecinse, and only a quarter of its length in 
Hapale and Lemur. 
The total length of the radius rather more frequently falls short of than exceeds that 
of the humerus. It exceeds it most in Tarsius and the Indrisinse. It also exceeds it, 
though not to such an extent, in Hylobates*, Loris, Perodicticus, Arctocebus, and, 
sometimes, at least, in Ateles f, Cynocephalus, Semnopithecus, and Simia. In all the 
others it is more or less shorter than the extreme length of the humerus, though in 
none so much so as in ManJ. 
The radius is thickest relatively in Cynocephalus, and then in Man. It is very 
slender in Ateles and Loris, but most so in Hylobates. 
The radius is always more or less curved, most so perhaps in the Gorilla and In- 
dris. It expands laterally at its distal end, but this expansion is least marked in 
Hylobates, Ateles, and the Nycticebinae. It is perhaps as marked in Man as in any 
other primate. 
The ulnar margin is sometimes sharp as in Man, the lowest Simiidae and others; 
sometimes it is rounded, as in Troglodytes, Hylobates, some Cebidae, Indris (PI. XII. 
fig. 6), and Loris. 
The outer margin is rather marked in Man, less so in Troglodytes and Simia, and 
* De Blainville says, “ L’avant-bras est encore plus long que le bras d’un septieme au moins ” ( loc . cit. 
p. 26). 
f Dr. Lucae, loc. cit. p. 286 (Table of Measurements and Proportions), makes the humerus longer than the 
fore-arm in all the American apes, but in no others, and both equal in Colobus ; yet at p. 287 he says that the 
humerus is the smaller in all the long-tailed apes, except Colobus and Ateles. 
+ In Brachyurus 1 (British Museum specimen) I have found the radius to be to the humerus as 75-9 to 100, 
and in the Boschisman as much as 81 to 100, so that in some exceptional cases the human proportion is 
surpassed-. 
