SUID^E 28 1 



spread over the Old World. Thus in the Upper Pliocene of the 

 Continent and the Pleistocene of England we meet with remains of 

 a very large fossil Hippopotamus which cannot be specifically 

 distinguished from H. amphibius. In the Pleistocene and Pliocene of 

 India there are two species having three pairs of incisors in both 

 jaws. Of these H. palceindicus has the second pair in the lower jaw 

 very minute, and evidently just about to disappear ; from which we 

 learn that it is this pair which is missing in H. amphibius. In the 

 still more generalised H. sivalensis the three incisors in the 

 lower jaw are of equal size. Hexaprotodont species also occur 

 in the Upper Tertiaries of Burma and Algeria. Small tetra- 

 protodont species (H. pentlandi and H. minutus) have left their 

 remains in enormous quantities in the caves and fissures of Sicily 

 and Malta. 



Family SUIDJE. 



An elongated mobile snout, with an expanded, truncated, nearly 

 naked, flat, oval terminal surface in which the nostrils are placed. 

 Feet narrow ; four completely developed toes on each. Hoofs of 

 the two middle toes with their contiguous surfaces flattened. The 

 outer (second and fifth) digits of existing forms not reaching to 

 the ground in the ordinary walking position. Teeth variable in 

 number, owing to the suppression in some forms of an upper incisor 

 and one or more premolars. Incisors rooted. Upper canines 

 curving more or less outwards or upwards. Stomach simple, 

 except for a more or less developed pouch near the cardiac orifice. 

 A caecum. Colon spirally coiled. Confined to the Old World. 



The mandible has no descending flange at the angle. The 

 crowns of the molars do not wear into such distinct trefoils as in 

 the Hippopotamus, and are oblong 

 in shape. The last molar of both 

 the upper and lower jaw (Fig. 102) 

 has an additional hinder lobe or 

 talon, varying in size in the different 

 species. The upper premolars are 



simpler than the true molars. FIG. 102. Grinding surface of a worn 



g us i Dentition : i f , c , p 4-, m third ri s ht lower molar of the Wild Boar 



., 1^1 jj TT 1' (Susscrofa). After Owen. 



f ; total 44. Upper incisors dimin- v 



ishing rapidly in size from the first to the third. Lower incisors 

 long, narrow, closely approximated, and almost horizontal in position, 

 their apices inclining towards the middle line ; the second slightly 

 larger than the first, the third much smaller. Canines strongly 

 developed and with persistent roots and partial enamel -covering, 

 those of the upper jaw not having the usual downward direction, 



1 Linn. Syst. Nat. 12th ed. vol. i. p. 102 (1766). 



