ON THE BONES OF THE HIPPOPOTAMUS. 409 



a, almost entire ; but what particularly enhances its value, is, that it 

 displays a much greater portion of the crotchet, b, and particularly a 

 portion of its posterior edge ; for the whole line, c d, is entire, and 

 without a fracture ; we may there see that this crotchet is stretched 

 farther backwards than in the living hippopotamus, and that that por- 

 tion of the jaw, instead of describing about the fourth of a circle, or the 

 half of a crescent, must form a sort of lunula. I have marked with 

 dots the contour which may be ascribed to that part, forming my 

 judgment on what has remained entire. 



Although this difference of configuration presents in itself a very 

 evident specific difference, the whole is not a less strong confirmation 

 of generic identity. As the common hippopotamus is the only known 

 animal which has this crotchet, we might be prepared to expect that, in 

 the event of the discovery of some other species of hippopotamus, this 

 characteristic would likewise be found ; but it is not by any means 

 requisite that it should have the same proportions. 



These two fragments of jaws must then have been recognised at 

 once as having proceeded from an hippopotamus, even though the nu- 

 merous teeth which accompanied them had never been subjected to 

 our inspection. 



This is also the case with a third fragment, represented at plate 34, 

 figs. 6 and 8, which is also taken from the block of M. Journu-Aubert. 

 It forms the third anterior of the lower jaw of the left side, and must 

 have belonged to a very young subject ; for on breaking it we only 

 found the germ of a canine tooth, still very hollow inside, and contained 

 in a socket larger than itself. Nevertheless, this square form of the front 

 extremity, which belongs to the lower jaw of the hippopotamus, and 

 to that animal alone, manifests itself clearly in this specimen. The 

 holes, perforated on the external surface to allow the exit of the maxillary 

 nerves, are placed in the same spot as in the common hippopotamus. 



The lower head of the humerus (plate 33, fig. 5), offers a simple 

 pulley at a, with a slight lateral excavation towards b. At this point it 

 resembles that of the pig ; but this second excavation would he much 

 stronger in the latter animal. It bears a further resemblance to that 

 of the pig, by the hole c, produced by the pressure of the olecranum in 

 the extension. 



Another part of the humerus, much more considerable and in a better 

 state of preservation (plate 34, fig. 2), was most decidedly distinguished 

 from the humerus of the pig by its sharp line, extremely prominent on 

 the outside, and commencing very low, precisely as it may be seen in 

 the humerus of the common hippopotamus. (See the osteology of the 

 living hippopotamus, plate 31, figs. 7 and 8, c)„ 



This portion, which only constituted two-thirds of the bone, was 

 0,13 in length. The two condyles were mutilated, so that it was 

 impossible to measure their distance from each other ; but the trans- 

 verse breadth of the articulating pulley was 0,045. I have found it 

 0,097 in the full grown animal, that is, a little more than double its 

 thickness. The lengths are in general a little more than double. 



The astragalus (plate 32, fig. 9) extracted from the block found in 

 the Musuem, is, if possible, still more characteristic. The edge, a, di- 

 viding the inferior part into two pullies of equal size, at once determines 



