424 OX THE FOSSIL BONES OF PACHYDERMATOUS QUADUUI'EI).-. 



The Humerus (ib., figs. 7, 8, 9, and 10) is very remarkable in this, 

 that its great tuberosity, a b, is a broad ridge, which is directed from 

 before backwards, and that the linea aspera, which is there triangular 

 instead of being linear, terminates inferiorly in a very prominent hook, 

 c. The anterior extremity, a, of the great tuberosity, forms a hook 

 anteriorly ; the small tuberosity, d, forms a similar one ; between both 

 there is a broad canal, which is no doubt for the tendon of the biceps. 

 All these characters will very well distinguish the humerus of the rhi- 

 noceros from that of every other large quadruped. The external condyle, 

 e, does not project much : the other, f does not at all project : the 

 inferior articulation is in the form of a simple pulley, a little oblique, 

 thicker on the inner side, hollow in the middle. 



The Radius (ib., figs. 14, 15, and 16) occupies, above all, the anterior 

 parts of the fore-arm ; its head, a b, is formed into a simple projecting 

 pulley of an oblong form, broader at the external edge ; it can only 

 flex, not turn; below it widens nearly as much as above, and termi- 

 nates by two sharp apophyses — an internal pointed one, c, and a trun- 

 cased one, d • the latter receives the semilunar bone ; between them 

 is a fossa which receives the scaphoid ; its greatest narrowing is 

 towards its upper third,/. 



The Cubitus (ib., figs. 11, 12, and 13), almost triangular in every 

 way, has towards the base a cavity, which receives a projection of the 

 radius : it terminates by a cavity for the cuneiform bone ; the ole- 

 cranon is very much compressed, enlarged at the extremity, and con- 

 stitutes the fourth of the entire bone. 



The Carpus of the rhinoceros (plate 43, fig. 5), and those of the 

 tapir and horse, are formed on a common model. However, the rhi- 

 noceros and tapir resemble each other much more than they resemble 

 the horse, whose bones in particular are more depressed, and have 

 their articulating surfaces flatter. 



The Scaphoid, a, has its upper facette nearly square, obliquely 

 very concave externally and posteriorly convex towards the external 

 anterior angle. A considerable ridge separates the trapezoidian fa- 

 cette from that of the os magnum, which are both in the form of a 

 hollow pulley. The trapezian facette is triangular and very small. 

 The superior external lateral facette for the semilunar bone extends 

 over its entire length. The inferior one, for the same bone, is but at 

 the anterior angle. 



The Semilunar bone, b, has its upper facette irregularly oval and 

 entirely convex, behind which there is a tuberosity inclining back- 

 wards and curved towards the lower part. Two elliptical facettes 

 correspond to the upper one of the scaphoid. The lower surface is 

 divided obliquely and irregularly into two concave facettes, one for 

 the posterior part of the upper facette of the os magnum ; the other 

 for the internal upper facette of the unciform bone, and behind this 

 there is still a rough portion. The anterior surface is square, and not 

 pointed upwards as in the hippopotamus. On the internal surface 

 there are two facettes for the cuneiform bone. The lower one occupies 

 the entire length of the bone. 



The Cuneiform bone has, as is usual, its upper surface concave and 

 descending obliquely towards the external edge ; the lower one is also 



