336 ME. ST. GEOEGE MIYAET ON THE SKELETON OE THE PBIIMATES. 
tab-ulum and spine of the ischium as in Man, Loris especially resembling the human 
structure in this. Of all the other Anthropoidea, Lagothrix perhaps makes the nearest 
approach to Man and Loris as to the tuberosity of the ischium (Plate XIII. fig. 1). 
The spine of the ischium is generally very small yet distinct. In European Man it 
presents a development much greater than that existing in any other Primate, though 
sometimes the Orang rivals certain of the inferior races of mankind in this respect. It 
is never so sharp a process, however, as it always is in Man. In Mycetes and Nycti- 
pithecus the spine of the ischium is hardly distinguishable. 
The great sciatic notch is never very deep and concave, except in Man. Of all besides, 
it is most concave in the Gorilla, Orang, and Cynocephalus. It is rather strongly so 
also in Indris. 
The lesser sciatic notch is generally represented by a margin which is so slightly 
concave as to be almost or quite straight, or even, as sometimes in Cynocephalus* * * § , 
slightly convex ; though in the lower Simiidse a concavity is often occasioned by the 
eversion of the tuberosity. The projection of the spine of the ischium produces in Man 
a deep notch such as exists in no other Primate. 
The acetabulum presents no very marked differences, but it is at its maximum of 
relative as well as absolute size in Man, Troglodytes, and Simia. It is largest and 
deepest, especially at the dorsal and towards the ventral side, in Man. In some of the 
Cebidse (e. g. Ateles, Lagothrix, Mycetes, Pithecia, and Callithrix) it is very shallow, 
and it is so besides in Indris. In all species it is deepest at the part corresponding with 
the upper wall of Man. 
The cotyloid notch and the excavation continuous with it are constantly present 
throughout the order, even in Simia f (where there is no lig amentum teres), though 
very small and narrow in that genus. In those skeletons of the Gorilla in which I have 
seen no trace of a depression for the round ligament on the head of the femur, the 
inner surface of the acetabulum is as usual J, or is but little less marked §. The notch 
is narrow in Ateles, but in Nycticebus it is sometimes relatively enormous ||. 
The general contour of the outer margin of the ischium, when the pelvis is viewed in 
front, is almost always more or less strongly concave. It is most so in the Gorilla and 
lowest Simiidse, but very little so in Ateles, less in Lagothrix, and still less in the Nycti- 
cebinse ; in Loris and Nycticebus, as in Man, being positively convex from the pro- 
longation upwards of the tuberosity. 
In all the Anthropoidea, except the Simiinse % about two-thirds of the acetabulum 
are visible when the outer surface of the ilium is looked at, but in the Simiinae it is only 
* E. g. No. 4719 in the Osteological Collection of the Eoyal College of Surgeons. 
t Its presence in the Orang- has been noticed by Mr. John Wood (Todd’s Cyclopaedia, vol. v. p. 153). 
J See No. 5179 a. College of Surgeons Museum. 
§ See No. 5179 b. College of Surgeons Museum. 
|| See Nycticebus javanicus in British Museum. 
This condition in Troglodytes is noticed by Professor Owen (Trans. Zool. Soc. vol. v. p. 14). 
