528 UNGULATES. 



enamel and cement alternate with the dentine in the substance of 

 the crowns of the complex molars. The pattern which characterises 

 the Ruminantia, and which is remarkable for its degree of constancy 

 in that Order, is shown in the upper and lower molar teeth in 

 PL 133. The next dental characteristic in degree of constancy is 

 the absence of incisors and canines in the upper jaw, and the 

 seeming absence of canines in the lower jaw, where those teeth are 

 so modified in shape and position as to resemble an external or 

 fourth pair of incisors. Two remarkable exceptions to this 

 character are, however, figured in PL 133 ; one in the genus 

 Moschus fig. 1, the other in the Auchenia, fig. 2. 



The ordinary dental formula of the Ruminantia is : — 



Incisors — : canines — : premolars — : molars — : = 32. 



3—3 ' 1— 1 ' ^ 3—3 ' 3—3 



The Antelopes, the Sheep, the Ox, representatives respectively of 

 the famihes Antilopid(S, Ovidts and Bovidcs, which are collectively 

 designated the ' hollow-horned' Ruminants(l), all present this formula. 

 It likewise characterises many of the ' solid-horned' Ruminants(2) 

 or the Deer- tribe {CervidcB), the exceptions having canine teeth in 

 the upper jaw in the male sex and sometimes also in the females, 

 though they are always smaller in these. In the male Muntjak 

 the upper canines protrude, like tusks, beyond the lips, descending 

 a little beyond the lower jaw ; and they had a like development 

 in the extinct Dorcathere. The upper canines attain their greatest 

 length in the small Ruminants called Musk-deer, and especially in 

 the typical species CMoschus moschiferusj most famous for the 

 preputial scent-secretion from which it takes its name : these teeth, 

 indeed, in the male Musk, present proportions intermediate between 

 those of the upper canines of the Machairodus and of the IMorse. (PL 

 133, fig. 1. c). The inverse relationship in the development of 

 teeth and horns exemplified by the total absence of canines in 

 the Ruminants with persistent and typical horns, by their first 



(1) From having persistent and commonly hollow bony processes of the skull supporting 

 hollow cones of true horny material. 



(2) From having solid bony processes undefended by horny sheaths, and which are annually 

 shed and renewed. 



