180 CHAEACTERS OF EVEN-TOED BEASTS. 



and the lower jaw combines with the like character an 

 unusual production and curvature of the angle. 



With regard to the osteology of the hog tribe, our 

 limits compel us to restrict ourselves to the notice of the 

 still more singular development of the sockets of the up- 

 per canines or tusks in the babyroussa, in which those 

 teeth carve upwards and pierce the skin of the face, like 

 horns, whence the name "horned hog" sometimes im- 

 posed upon it. 



If the hoofed animals with the digits in even number 

 be compared together, in regard to their osteological cha- 

 racters, they will be found, notwithstanding the difference 

 of form, proportion, and size presented by the hippopo- 

 tamus, wild boar, vicugna, and chevrotain, to agree in 

 the following points, which are the more significative of 

 natural afl&nity when contrasted with the skeletons of the 

 hoofed animals with digits in uneven number. Thus, in 

 the even-toed or " artiodactyle" ungulates, the dorso-lum- 

 bar vertebrae are the same in number, as a general rule, 

 in all the species, being nineteen. The rare exceptions 

 appear to be due to the development, rarely to the sup- 

 pression, of an accessory vertebra as an individual vari- 

 ety, the number in such cases not exceeding twenty, or 

 falling below eighteen, and the supernumerary vertebra 

 being most usually manifested in the domesticated and 

 hiofhly-fed breeds of the common hog. The recognition 

 of this important character appears to have been impeded 

 by the variable number of movable ribs in different spe- 

 cies of the artiodactyles, the dorsal vertebra, which these 

 ribs characterize, being fifteen in the hippopotamus and 

 twelve in the camel ; and the value of this distinction has 

 been exaggerated owing to the common conception of 

 the ribs as special bones, distinct from the vertebrae, and 



