384 ox THK FOSSIL BO^fES OF PACHYDERMATOUS QUADRUPEDS. 



The carpus of the hippopotamus is in its general form shaped on the 

 model of that of the pig, but its bones are less elevated and more 

 depressed. Those of the first rank have their superior surfaces more 

 concave from front to rear. The scaj)hoid, a, (fig. 1,3, plate 31), has 

 a posterior tuberosity more salient. The semi-lunar, b, (ib.) has its an- 

 terior surface rising more obliquely towards the outside, audits superior 

 externalangle more pointed. The os cuneiforme, r:/,isless compressed on 

 its sides. The os pisiforme, e, is also less compi'essed ; it has a thick round 

 projection on its external surface, which gives it a crooked appearance. 



In the second rank, a small pointed bone, f, almost similar to the os 

 pisiforme, serves for a toe and a trapezium. The trapezoid, g, is not 

 compressed on the sides, like that of the pig, but is broader than it is 

 high. The facette for the trapezium occupies the whole height of its 

 external surface. Its superior surface is a slightly convex trapezium. 

 The large bone, h, has scarcely any anterior surface, it is so much de- 

 pressed ; and behind its double upper surface it has a tuberosity, or 

 more properly a long crooked pediculum, which does not exist in 

 the pig. 



The ridge which separates the two upper facettes in the unciform, i, 

 is less oblique than in the pig ; the exterior of the two is less extended 

 on the outside; and there is, behind, a pediculum, as in the great bone, 

 which does not exist in the pig. 



All these characters of the carpus of the hippopotamus are as 

 strongly distinguished from those of the ox as from those of the pig. 



Its metacarpus, only, can bear comparison with that of the pig, but 

 all its bones are thicker and shorter. The two extremes,^, /, (fig. 13, 

 plate 31), are shorter, but thicker than those of the centre, m and n; 

 the antero-posterior diameter of their upper extremities is more con- 

 siderable in proportion, and the articular pullies of their inferior 

 extremities are simple, scarcely discovering behind the vestige of a 

 middle edge. The phalanges have the common articulations. The 

 second are shorter by one half than the first; and the third are the 

 smallest of the set, and are of a semicircular form. 



V. The posterior Extremity. 



The pelvis of the hippopotamus, G, (fig. 1, plate 30, and fig. 14, 

 I^late 31), is easily distinguished from those of the elephant and the 

 rhinoceros, as it is much smaller in the direction of the ilia, and as the 

 large ileal wings approach nearer to a common plane than the necks of 

 the ossa ilium : the ischia and tlie pubis are more elongated, and the 

 latter less salient, so that the strait is very oblique, and the small 

 pelvis very much elongated. Here, again, it is the ox which approaches 

 the nearest to it in these particulars ; but, in the hippopotamus, the 

 smaller pelvis and the ovalar holes especially are more elongated. The 

 shape too of the ■^ddened part of the ossa ilium is also very diiferent ; 

 their two wings are almost equally exuberant; the external is larger 

 and more rounded than the other, v.'hich is more pointed. The contrary 

 is the case in the ox and in the camel. The anterior margin which unites 

 them forms the convex are of a circle ; in the ox it is shaped thus, co. 

 The camel has it in common v/ith the hippopotamus, but without any 

 direct resemblance in other respects- For instance, the tuberosity of 



