SUIDE 281 
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 A. palwindicus 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. siralensis 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 (A. pentlandi and H. minutus) have left their 
remains in enormous quantities in the caves and fissures of Sicily 
and Malta, 
Family Svip®. 
An elongated mohile 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 fattened. 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 cardiae orifice. 
Acreum. 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. Fie. 102,.—Grinding surface of a worn 
Sus.t—Dentition: Ee c 1, p 4, m third right lower molar of the Wild Boar 
8; total 44. Upper incisors dimin- 6°72") Aferowen. 
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 shghtly 
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. Srsf, Not, 12th ed. vol. ip. 162 (1760). 
