HOG-TRIBE. 545 



incisors of the lower jaw, whose crowns oppose their upper sides 

 to the ends of those above, as in the herbivorous Marsupials. 

 But the incisors in the Hog are six in number below, as well 

 as above : they are long, sub-compressed, nearly straight ; the 

 second is rather larger than the first; the third is the smallest, as 

 in the upper jaw\ In the two larger procumbent incisors the crown 

 is remarkably long, and the enamel continued far into the socket, 

 especially upon the upper and under surfaces ; the under surface is 

 slightly convex and even ; the upper one has a peculiar character 

 in a strong median longitudinal rising, divided by a depression on 

 each side from the two margins of the crown, of which the outer 

 one forms a dentated ridge ; these characters become obliterated 

 by use, but the lateral flattening or compression of the long and 

 straight fang may assist in the determination of one of these 

 incisors. The lateral incisor curves towards the second. 



The upper canines, in the Wild-boar, curve forwards, out- 

 wards, and upwards ; their sockets inclining in the same direction, 

 and being strengthened above by a ridge of bone which is extra- 

 ordinarily developed in the Masked Boar of Africa. The enamel 

 covering the convex inferior side of this tusk is longitudinally 

 ribbed, but is not limited to that part ; a narrow strip of the 

 same hard substance is laid upon the anterior part, and another 

 upon the posterior concave angle forming the point of the tusk, 

 which is worn obliquely from before upwards and backwards to 

 that point. I have never seen a permanent upper tusk of either 

 sex of the Sus scrofa in which the enamel was limited to the 

 outer surface as described by M. Rousseau(l) : in the lower tusks 

 it covers the anterior and inner as well as the outer sides. The 

 longitudinal ridges on the lower plate of enamel are fewer and 

 stronger in the Masked Boar {Sus larvatus) than in the common 

 Wild Boar. In the Sow the canines are much smaller than in 

 the Boar. In some domestic breeds the upper tusk has a short 

 descending pointed crowm, with an anterior and posterior margin, 

 divided by indentations from a median convexity, something like 



(1) 'Anatomic Coraparee du Systeme Dentaire,' p. 206. 



N N 



