1872.] SIR VICTOR BROOKE ON HYDROPOTES INERMIS. 523 



the bulla from before backwards. The tympanic is considerably 

 prolonged to form the inferior floor of the external auditory meatus. 

 Correlated with this great difference in the size of the auditory 

 bulla, the basioccipital is much wider relatively in Moschus than 

 in Hydropotes, being raised into a low median ridge, whereas in 

 Hydropotes this bone is rather narrow and slightly grooved from 

 the foramen magnum forwards. In Hydropotes the praemaxillae are 

 very much shorter and broader than in Moschus. The rami of the 

 lower jaw in Hydropotes, from the dental foramen to the external 

 incisor, are very much compressed from side to side, and raised into 

 sharp laminated everted edges, in adult specimens a quarter of an 

 inch in height. In Moschus there is no trace of this curious for- 

 mation. 



In dentition the most remarkable difference between Hydropotes 

 and Moschus lies in the form and direction of the incisors. In 

 form, those of Hydropotes resemble the ordinary ruminant type ; 

 in direction, their axes form an angle of about 45° with that of the 

 rami. In Moschus the edges of the incisors run almost parallel, 

 there being but little tendency to flattening and widening out, the 

 series presenting unusual equality in size ; their direction is but 

 slightly removed from the plane of the lower jaw. Both in form 

 and direction they bear a singular resemblance to the incisors of the 

 Reindeer, and are possibly special adaptations in widely separate 

 forms of Cervidce to like functional purposes. 



The molar series presents no striking difference between the two 

 genera under consideration. In Hydropotes the teeth are, perhaps, 

 somewhat wider from side to side, especially the premolars, than 

 they are in Moschus; their formula would stand, P. ^. M. -f . 

 as in other ruminants. The canines of Hydropotes are very power- 

 ful, apparently not reaching to so great a length as in Moschus, 

 but exceeding them greatly in massiveness. As these teeth attain 

 their maximum of development the pulp-cavity contracts, accom- 

 panied by the gradual protrusion of the root of the tooth. In the 

 younger male (fig. 1, p. 524), which exhibits the three milk-molars 

 along with the two auterior true molars, it will be perceived that the 

 large open proximal end of the canine is situated as far up as the ante- 

 orbital vacuity. In an adult male (fig. 2) presenting the full series 

 of permanent teeth, the canine has advanced the distance of about an 

 inch downwards from the position observed in the younger animal, 

 and the pulp-cavity is greatly contracted. In (fig. 3) that of the 

 fine old male presented by Dr. Hamilton, the canine has protruded 

 still further, and the pulp-cavity is entirely obliterated. This same 

 process takes place in Moschus and in Cervutus — in the former 

 more slowly, in the latter more rapidly than in Hydropotes. 



Conclusion. — So far as the materials at my command have en- 

 abled me to form an opinion as to the position Hydropotes inermis 

 would occupy in a systematic arrangement of the Cervida?, it appears 

 to present sufficiently aberrant characters to separate it from any of 

 the known forms. It must, however, be left for further knowledge 

 of the species to determine the essential importance of these cha- 



