426 ON THE FOSSIL BONES OF PACHYDERMATOUS QUADRUPEDS. 



still more remarkable than its humerus : its upper part is extremely 

 flattened from before backwards ; the eminence, a, which I call a third 

 trochanter, projects very much, and forms a hook, which ascends to 

 touch a descending hook of the ordinary great trochanter, b, so that a 

 foramen ovale remains between these two eminences. The inferior 

 pulley, c, is very narrow anteriorly; the internal edge, d, is much 

 more prominent there, and ascends higher than the other, e. Posteriorly 

 the two condyles, f g, are more separated than anteriorly, but they 

 form nearly the same projection. 



The Tibia (ib., figs. 17, 18, and 19) has its head in the form of an 

 equilateral triangle : only the posterior internal angle forms a hook- 

 like projection ; the anterior angle forms a very great tuberosity be- 

 neath the patella. The lower part of the tibia is a little flattened 

 from before backward. The fibula is thin, compressed laterally, and 

 enlarged at its two extremities. 



The Tarsus and upper part of the metatarsus (plate 43, fig. 4) are 

 constructed on the model of the horse ; only the pulley of the astra- 

 galus, b, is broader, less oblique, and less deep : its posterior internal 

 angle is obliquely truncated ; the astragalus touches the cuboid, c, by 

 a tolerably broad facette ; the schaphoid, d, and the third cuneiform are 

 less flattened ; the second cuneiform and the cuboid are greater. In 

 all these points the rhinoceros resembles the tapir more than the horse, 

 and it may even be said, that were it not for the size, it could scarcely 

 be distinguished from the first ; but it differs from all two by an os 

 calcis, which is thicker and shorter. Its anterior or astragalian surface 

 is triangular. There are two broad facettes for the astragalus ; that 

 of the internal side is prolonged into a sort of tail all along the inferior 

 edge of this surface, as in the tapir. In the horse the third facette 

 towards the external angle is distinct. The facette which touches 

 the cuboid is very small. 



The facettes of the astragalus (ib., b) are the counter-part of 

 those of the os calcis ; the two edges of its pulley are of equal height. 

 The part of the anterior surface which touches the cuboid is narrow. 



The cuboid, c, has posteriorly a long and thick protuberance, which 

 is not in the horse. At the internal side of the foot, there is a similar 

 one produced by a supernumerary bone attached to the scaphoid, to 

 the internal cuneiform, and to the internal metatarsal bone, and which 

 represents at once the first cuneiform and the thumb in its entire 

 extent. This bone exists also in the tapir and the horse, but in the 

 latter it soon becomes united with the second cuneiform. The sca- 

 phoid, d, has then three articulating facettes at its lower, or rather me- 

 tatarsal surface ; the third, or internal cuneiform, e, is much smaller 

 than the other,/ 1 . 



The external Metatarsal, g, is articulated only with the cuboid, and 

 touches the middle metatarsal, h, by two facettes of the inner edge of 

 its head : the latter is articulated only with the great cuneiform ; it 

 has two smaller facettes for the external. This latter, i, touches the 

 preceding and the great cuneiform bone by the internal side, and the 

 supernumerary bone by the external ; it has only one facette for this 

 bone. 



ThePIialanges are all more broad than long; the second of the 



