182 MK. ST. G. MIVAET ON THE SKELETON OF THE PEIMATBS. 



exceeding the breadth of the two tuberosities, in which respect Simia differs from both 

 Man and Troglodytes (PI. XXXVI. figs. 5 & 6). 



The posterior projection of the head is greater than in Man and the Gorilla, the 

 bone immediately below the posterior part of the margin of the articular surface being 

 more concave (PI. XXXVI. fig. 4). The anatomical neck is more marked than in the 

 higher forms, especially than in Man, and the head rises more above the summit of the 

 radial (greater) tuberosity. 



The angle formed by the groove separating the last-named tuberosity from the head, 

 with a line connecting the two condyles, is in general much more acute than in Man 

 and Troglodytes. There is nevertheless considerable individual variation, the angle 

 bemg sometimes as near a right angle as in the Gorilla (PI. XXXVI. fig. 5), while in 

 other instances (PI. XXXVI. fig. 6) it is only about 34° ; yet, in all the specimens of 

 Simia which I have examined, the head looks more directly backwards and less 

 inwards than in Man and Troglodytes. 



The radial tuberosity in the Orang is less prominent than in the Gorilla, and but 

 little more so than in Man, though the surface for the teres minor is more sharply 

 defined than in the higher forms (PI. XXXVI. fig. 3). The surface for the infra- 

 spinatus looks more outwards and less upwards than in Man (PI. XXXVI. fig. 3). 



The ulnar, a smaller tuberosity, has its upper part next the bicipital groove less 

 prominent than in Man or Troglodytes. Sometimes its lower part is more prominent 

 than its upper portion. This tuberosity is more nearly approached by the margin of 

 the articular surface of the head than in the higher forms ; so that there is a small deep 

 pit (PL XXXVl. fig. 4) between them, instead of a rather wide and slightly concave 

 surface. 



When the humerus is vertical, and its anterior surface opposite the observer, the 

 iiinar tuberosity generally hides part of the lower margin of the neck of the bone, 

 in which respect Simia resembles Troglodytes and difiers from Man\ As in higher 

 forms, no part of the head of the humerus is so hidden in the Orang. 



At the lower end of the bone the ulnar, or inner, condyle is not so prominent as in 

 Man or Troglodytes, nor does it extend so much downwards as in Man and the Chim- 

 panzee, but appears as if it had been truncated obliquely from below upwards and 

 ulnad, though this appearance is not so marked as in the Gorilla, on account of the 

 less prominence of the condyle in the Orang. As in Troglodytes, there is not that 

 concavity on its posterior surface which is more or less marked in Man. 



The external, or radial, condyle is much as in Man and the Chimpanzee, and its most 

 prominent point is situated lower down than in the Gorilla. 



The inferior articular surface of the humerus is almost quite as in Man, except that 

 its innermost part generally descends less below the rest of the surface than in him 

 or the Chimpanzee, though more so than sometimes is the case in the Gorilla. 

 ' Owen, Trans. Zool. Soc. vol. v. p. 4, pi. 3. figs. 1, 5, S. 



