1838.] On the genus Hexapvotodon. 1041 



another argument may be adduced in support of the above view of the 

 habits of these animals from the cheek teeth being extended at shorter 

 and more regular intervals along the sides of the jaws to the canines, a 

 structure which we may suppose to be more essential to the use of a 

 soft food. As a share of Colonel Colvim's extensive collections, com- 

 prising I believe many specimens of these animals, has been presented 

 to the museum of the University of Edinburgh, we may expect the 

 subject to receive the attention which it deserves, but at present we 

 must I think, regard the type as more aquatic than that of the hippopo- 

 tamus. 



Dr. Falconer and Captain Cautley conceive that the genus Hip- 

 popotamus of LiNNiEUS was confined to Africa and Europe, and that its 

 place has been supplied in India by the Hexaprotodons : in this they are 

 probably correct, but there is one specimen (fig. 3.) in Col. Colvtn's 

 collection which though very imperfect appears to render the ques- 

 tion at least somewhat doubtful ; the two inner incisors being indicated 

 by the remains of their fangs, and a single small outer incisor oc- 

 cupying the centre of the space between the large incisor on the left, 

 and the canine tooth, with a proper space on the opposite side, in which 

 however, all trace of a corresponding tooth is obliterated. A careful 

 examination of all the specimens in the museum, would also lead us to 

 suppose that there must have existed in India more species of the new 

 group than the two which Dr. Falconer and Captain Cautley have 

 described, and I should be disposed to think the specimens alluded 

 to tend to countenance the probability that four species existed, 

 although our materials are hardly to be considered satisfactory on this 

 point : from the importance of the subject it is desirable that the 

 contents of every museum, so far as they are capable of bearing upon 

 the question, should be known, so that the contents of one collection 

 might illustrate those in another. I will therefore attempt to describe the 

 separate specimens which I have examined. To show how far these 

 fragments differ among themselves as well as from the corresponding 

 parts of the existing hippopotamus (fig. 1.) and the principal species 

 of the same fossil found in Tuscany (tig. 2.) the upper view of the 

 lower jaws of those species are given for comparison. 



Fig. 3. is the front portion of an imperfect lower jaw in Colonel 

 Colvin's collection ; it has one large incisor on either side of the mesial 

 line, with a small one in the intermediate space on the left side as in 

 the hippopotamus, so that a third could not have existed on that side ; 

 but all trace of a corresponding incisor between the canine on the 

 right side, and the inner incisor is obliterated, though the proper space 

 for one remains. This appears to be the H, dissimilis, Falc. Caut. 



