314 
ME. ST. GEOEGE MIYAET ON THE SKELETON OE THE PEIMATES. 
The anterior surface is generally not so depressed for the origin of the flexor 'pro- 
fundus as in Man and Simia. The surface answering to the anterior and inner ones of 
Man is concave in Ateles and some other Cebidse, and very much so in Lemur. 
There is a deep depression for this last-mentioned muscle (inside the olecranon, or 
beneath the greater sigmoid cavity) in the Gorilla and Orang, the Simiidse other than 
the Simiinse, the Cebidse (except Ateles), and the Lemuroidea. 
In Loris and Indris there are no excavations or marked depressions for muscular attach- 
ment on the shaft of the bone, which is very rounded and cylindrical (PL XII. fig. 7). 
The fossa for the origin of the extensores pollicis is marked in Man, and much so 
below the surface which gives attachment to the anconeus ; as also in Simia and Hylo- 
bates. In Troglodytes it is much less so, and still less in the lower Simiidse, except at 
the proximal end of the radial surface of the ulna. It is very slightly marked in Ateles 
and Mycetes, but more so in Lagothrix and Cebus ; but slightly in the other Cebidse, 
except Chrysothrix, in which, as also in Hapale, it is very marked. It is very marked 
in Lemur and Galago, less so in the other Lemuroidea. 
The surface of the supinator brevis is marked and deep in Man and Troglodytes, less 
so in Simia and ILylobates. It is longer, but narrower relatively, in the Simiidse other 
than the Simiinse. In the Lemuridse* it is absent. 
The place of attachment of the anconeus is more marked in Man and Simia than in 
Troglodytes. In Hylobates, for the first time in descending from Man, it does not 
extend so high up as the upper margin of the lesser sigmoid cavity ; and in the other 
lower forms of the order I have not found any fossa marked off from that for the 
extensores pollicis. 
The ridge for the attachment of the pronator quadratus is very slightly marked 
indeed in Man, and very little more so in Troglodytes and the lower Simiidse ; w T hile in 
the lower Cebidse, Indris, Galago, and most Nycticebinse it is rudimentary or absent. 
On the other hand, it is sometimes marked in Simia, and occasionally still more so 
in Hylobates, the Cebinse, Mycetes, and Hapale, and also more or less in Cheiromys, 
but it attains its maximum of development in Lemur. 
The head of the ulna is large and rounded in Man and Troglodytes. It is more 
transversely extended in Simia, and in all below is much smaller as compared with the 
styloid process, especially in Ateles, Hapale, Lemur, and Galago. It is rather larger 
again in Indris and the Nycticebinse. 
The styloid process is of moderate length in Man ; it is shorter in the Gorilla, and 
still more so in the Orang. In the Chimpanzee it is longer and more curved ; also in 
Hylobates, where it developes a peculiar prominence from its hinder side (for the internal 
lateral ligament of the wrist), which prominence also sometimes exists in the Cynopi- 
thecinse and in Indris. The styloid process is very elongated in the Cebidse generally ; 
but in Ateles it becomes enormous, having a rounded articular head placed, as it were, 
at the end of a peduncle, and being really much more the continuation of the shaft of 
* This muscle has no connexion with the ulna in Lemur. 
