182 PROF. W. H. FLOWER ON THE MUSK-DEER. | Mar. 16, 
the Cervide by the absence of canine teeth, by the absence of distinct 
metacarpals and phalanges to the outer (second and fifth) digits, by 
the presence of a gall-bladder, by the single lachrymal canal placed 
within the margin of the orbit, and by the presence of Cowper’s glands. 
But yet, as will be shown presently, it is doubtful if any one of these 
characters is exclusively characteristic—that is, may not be found 
in some member of the other groups. 
There is still another character of some importance, derived from 
the form of the molar teeth. Although there is nothing in the 
general mode of arrangement of the enamel-folds or in the accessory 
columns absolutely distinctive between the two groups, existing 
species can generally be distinguished, inasmuch as the Deer are 
what may be termed “brachyodont,” and the Bovide ‘ hypso- 
dont’”’*: i.e. the teeth of the former have comparatively short 
crowns, which, as in most mammals, take their place at once with the 
neck (or point where the crown and root join) on a level with or a 
little above the alveolar border, and remain in this position throughout 
the animal’s life; whereas in the other form (the crown being 
lengthened and the root small) the neck does not come up to the 
alveolar level until a considerable part of the surface has worn away, 
and the crown of the tooth thus appears for the greater part of the 
animal’s life partially buried in the socket, and no part of the root 
is visible. In this form of tooth (which is always most developed in 
the posterior molars of the permanent series) the constituent columns 
of the crown are necessarily nearly parallel, whereas in the other 
they diverge from tie neck towards the free or grinding surface of 
the tooth. In the more completely hypsodont forms, the interstices 
of the lengthened columnar folds of enamel and dentine are filled up 
with cementum, which gives stability to the whole organ, and which 
is entirely or nearly wanting in the short crowned teeth. 
The same modifications from low to high crowns without essential 
alteration of pattern is seen in an even still more marked manner in 
some of the Perissodactyle Ungulates, where the tooth of a horse 
bears to that of Anchitherium the same relation that that of an ox 
does to the early Selenodont Artiodactyles. 
As the hypsodont tooth is essentially a modification of, and, as it 
were, an improvement upon, or specialization of, the other, it is but 
natural to expect that all intermediate forms may be met with ; and 
it is not always easy to decide, especially in old and much-worn 
teeth, in which group any given example should be classed. Even 
among the Deer themselves, as Lartet has observed, the most ancient 
have very short molars, and the depressions on the grinding-surface 
are so shallow that the bottom is always visible, while in the Cervide 
of the more recent Tertiary periods, and especially the Pleistocene 
and living species, these same cavities are so deep that, whatever be 
the state of the dentition, the bottom cannot be seenf. 
* Terms first used, I believe, by Mr. Boyd Dawkins. 
~ + Comptes Rendus, 1868, t. lxvi. p. 1119. 
+ Some existing Deer, as the Axis, are far more hypsodont than the majority 
of the family; and, on the other hand, many of the Antelopes are far more 
brachyodont than the more typical Bovid~—Goats, Sheep, and Oxen. 
