348 



ANATOMY OF VERTEBRATES. 



deciduous molar, d 3, has a large trilobate crown, the first lobe small, 

 with an anterior basal ridge ; the second large, conical, with three 

 longitudinal indentations ; the third lobe still larger, and cleft into 

 two half-cones by an antero-posterior fissure assuming the normal 

 pattern of the true molars. The third deciduous molar, d 4, above 

 more closely resembles the ordinary upper true molar ; but its 

 second pair of demi-cones are relatively larger. In the lower jaw 

 the last deciduous molar, d 4, has a more complex crown than that of 

 any other teeth of the permanent or deciduous dentition. It has 

 three pairs of demi-cones, progressively increasing in size, from 

 before backward, with an anterior and posterior basal ridge and 

 tubercles. Like the last trilobate deciduous lower molar of the 

 Hog, it increases in thickness posteriorly, instead of diminishing 

 here, like the last true molar of the lower jaw of the adult Hippo- 

 potamus. 



The upper incisors, and the first premolar of both jaws, are not 

 developed in the typical Ruminants, rarely the upper canines : 

 the dental formula being : — 



0.0 0.0 3.3 



p 



* — : c — 

 3.3' 1.1 



3 3 

 '- = 32 (vol. 



.474, fig. 324). 



The gazelle, the sheep, the ox— respectively representing the 

 families Antilopidce, Ovidce, and Bovidce, which are collectively 

 designated the ' hollow-horned ruminants ' — all present this 

 formula. It likewise characterises many of the solid-horned 



ruminants, or the deer tribe 

 ( Cervidce), the exceptions hav- 

 ing canine teeth in the upper 

 jaw of the male sex, and 

 sometimes also in the females, 

 though they are always smaller 

 in these. 



The upper canines attain 

 their greatest length in the 

 Muntjac (vol. ii. p. 478, fig. 

 328, a a) and the small Musk- 

 deer, and especially in the 

 typical species (Moschus moschiferus, fig. 277.) These teeth, in- 

 deed, in the male Musk, ib. c, present proportions intermediate be- 

 tween those of the upper canines of the Machairodus and of the 

 Morse. The inverse relationship in the development of teeth and 

 horns, exemplified by the total absence of canines in the Rumi- 

 nants with persistent frontal weapons, by their first appearance 



1 The line traverses the Cuvierian ' dents carnassieres ' ; the interrupted line tra- 

 verses the Blainvillian ' dents principales '. 



Dentition, Mosclms moschiferus.' 





