342 
ME. ST. GEORGE MI V ART ON THE SKELETON OE THE PRIMATES. 
least of all in the Orang, where the length of the femur is less than seven-tenths of 
that of the humerus. 
The proportion in length borne by the tibia to the radius is greatest, again, in Tarsius, 
viz. as 163’8 to 100. In TIapale it is as about 158-6, in Man about 150'5 to 100, 
and hi Callithrix as 149T. In all the rest the length of the former bone is in excess, 
or the two are equal, except sometimes in Cynocephalus, and in Ateles and the 
Simiinee. 
The breadth between the tuberosities, compared with the extreme length of the tibia, 
varies from about 28’5 to 100, as in the Gorilla, to only 9‘8 to 100, as in Tarsius. 
The antero-posterior diameter of the shaft also, compared with the length of the bone, 
varies from about 14-6 to 100 in the Gorilla, to about 6 to 100 in Loris. 
The tibia is most laterally compressed in Tarsius, most cylindrical in Loris. It is most 
massive in Troglodytes and Simia. 
The tubercle of the tibia is more distinctly prominent in Man than in other Primates. 
It is situated higher up, as regards the rest of the bone, in him than in any other of the 
Anthropoidea. In Indris it is as high up as in Man, and in Tarsius it is still higher. 
The smooth surface above the rough projection of the tubercle is larger in the Simiinae 
than in Man. 
The tuberosities project out considerably on each side, except in Tarsius; and in most 
Primates the peroneal one projects outwards more strongly than it does in Man. 
A process is sometimes developed above the surface for the tibialis anticus , and pro- 
jects sharply outwards. This is well seen in the Lemuroidea, except Tarsius, and is 
visible also in Mycetes. The amount of projection of the inner tuberosity varies but 
little, except that in Tarsius it is very slight. 
The articular facets for the condyles of the femur rarely occupy the summit of the 
tibia so completely as in Man. 
The outer facet is always decidedly convex antero-posteriorly, except in Ateles, Lago- 
thrix, Indris, and Man, where it is flat or slightly concave antero-posteriorly. 
The inner facet is almost always concave antero-posteriorly as well as transversely, but 
it is almost quite flat in Indris, while sometimes in the Lemuroidea ( e . g. Galago and 
Perodicticus) its posterior part inclines strongly downwards. 
The spine is always of moderate height, much as in Man, but is longest relatively per- 
haps in Indris. 
The peroneal surface of the shaft is often much excavated for the tibialis anticus , and 
most so in Lemur. 
The crest of the tibia is sometimes very prominent, as in Tarsius, Man, Lemur, and 
Indris. It is generally much sharper, however, in Man than in any other Primate. 
The shaft of the tibia may be straight or variously curved. It is straight, or almost 
so, in Man, Lagothrix, Pithecia, Indris, and more or less so in Ateles and the Orang. 
It is considerably curved, convex forwards, in the Gorilla, the lower Simiidae, and 
Lemur. 
