MR. ST. G. MIVART ON THE SKELETON OP THE PRIMATES. 181 



atlas to the lower end of the sacrum — a proportion decidedly exceeding that existing in 

 the Chimpanzee, and greatly so that found in Man. 



It is nearly twice the length of the scapula, which is less than in Man, though more 

 than in Troglodytes. 



The humerus of the Orang is not so straight as that of Man, the Gorilla, or Chim- 

 panzee, but is more bent concave forwards, and sometimes' very much so (PI. XXXVI. 

 fig. 3). It is also more incluied ulnad at its lower end, the inner margin of the 

 bone being decidedly concave (PL XXXVI. fig. 2). 



As in Man and Troglodytes, the shaft may be described as consisting of three surfaces ; 

 but these are not well defined, the lowest fifth of the anterior surface not being so 

 sharply prominent as in Homo. Thus the shaft is not so decidedly triangular at its lower 

 part as in Man, neither is it so compressed laterally towards its middle as is generally the 

 case in him, the Orang in both these respects agreeing more with Troglodytes. 



The ridges proceeding upwards from the condyles are more marked than in Man or 

 Troglodytes, especially the external one (or supinator ridge), which extends rather more 

 than one-third up the shaft, and is sometimes limited above by a marked musculo-spiral 

 groove. The ridge from the internal condyle extends about halfway up the shaft. 



The posterior surface of the humerus is convex above, much as in Man, not flattened 

 as in the Gorilla. Below, it is flat, as in the superior forms ; it is not, however, turned 

 so much outward as in them, but looks backwards, indeed almost equally with the 

 upper part of the posterior surface (PL XXXVI. fig. 2). 



The bicipital groove is sometimes more marked than in Man, and more sharply limited 

 on each side at its upper part, though less so there than m Troglodytes. Lower down 

 it is often more marked than in that genus, or than is generally the case in Man. 



The surface probably serving for the insertion of the coraco-hracMalis is extraordinarily 

 rugose, more so than it ever is, as far as I have observed, in Man, and sometimes 

 more so than in the Gorilla, much more so also than in the Chimpanzee ; the rough- 

 ness sometimes extends so far downwards as to join the ridge extending upwards 

 from the internal condyle (PI. XXXVI. fig. 4 c). 



Near the surface for the coraco-brachialis, and a little below or a little above the 

 middle of the bone, is the medullary foramen opening distad, as in Man. 



The surface for the deltoid is not so much raised as is generally the case in Man ; 

 and below it is the more or less distinct oblique depression marking the course of 

 the musculo-spiral nerve and artery (PL XXXVI. figs. 1 & 25). 



The head of the humerus is very large- and rounded, its greatest diameter decidedly 



' As in both the humeri of Xo. 3 B in the British Museum. 



= Professor Owen says, "it is larger in Simia satyrus than in man, its extent equaUing a complete hemi- 

 sphere" (Trans. Zool. Soc. vol. i. p. 364). De BlainviUe remarks, "sa tete articulaire est surtout sing.i]iiTc 

 par son enormite, son diamctre etant bien supericur a cclui de la tete du femur" (Osteographie, " Primates: 

 PUhecus," p. 30). 



