HIPPOPOTAMUS. 571 



209. Succession. — The true natural affinities of the Hippopotamus 

 are clearly manifested by the character of its deciduous dentition ; 

 and, if this be compared with the same dentition in other Ungulata, 

 it will be seen, by its close correspondence with that of the Hog- 

 tribe, and more especially with the Phacochere, that the Hippo- 

 potamus is essentially a gigantic Hog. The formula of the teeth 

 which are shed and replaced is : 



. 2-2 1-1 3-3 ^. 



2—2 * 1— I ' 3—3 



If the simple premolar which is developed anterior to the deciduous 

 molars, and which has no successor, be regarded from its early 

 loss in the existing Hippopotamus, as the first of the deciduous 

 series, we must then reckon, with Cuvier, four milk molars on each 

 side of both jaws. The incisors in both jaws are simply conical 

 and subequal, with an entire cap of enamel on the crown. The 

 deciduous canines scarcely surpass them in size in the upper jaw, 

 and not at all in the lower; projecting forwards here, from the angles 

 of the broad and straight symphysis, they appear like an additional 

 pair of incisors ; and we have seen that the character of equality 

 of development was retained, with the more typical number of in- 

 cisors, by the ancient form of Hippopotamus which formerly inhabited 

 India. The first true deciduous molar {d 1) has a conical crown 

 and two fangs in both jaws : that above has also a conical crown 

 with one strong posterior and two anterior ridges. The second 

 deciduous molar has a large trilobate crown, the first lobe small 

 with an anterior basal ridge ; the second large, conical, with three 

 longitudinal indentations ; the third lobe still longer and cleft into 

 two half cones by an antero-posterior fissure assuming the normal 

 pattern of the true molars ; the third deciduous molar above more 

 closely resembles the ordinary upper true molar, but its second pair 

 of demi-cones is relatively larger. In the lower jaw the last deci- 

 duous molar has a more complex crown than that of any other tooth, 

 whether of the permanent or deciduous dentition(]) ; it has three pairs 

 of demi-cones, progressively increasing in size, from before back- 

 wards, with an anterior and posterior basal ridge and tubercles : 



(1) This tooth is described as the first of the four true molars by M. F. Cuvier, loc. cit. 

 p. 207 ; but its true nature was recognised by Baron Cuvier, see * Ossemens Fossiles,' 4to. i. 

 p. 289 



