1873.] SIR V. BROOKE ON THE GENUS GAZELLA. 551 



rufous tint than the fawn-colour of the shoulders, upper parts of the 

 back, and haunches. Ears long. Horns in both sexes, but very 

 small in the female ; in the male they are truly lyrate, strongly 

 annulated, and massive, of moderate length. Knee-brushes absent. 

 Height at shoulder about 30". 



Skull : nasal bones rather elongated and pointed. Dentition i.-j, 



c '~i> P* 2» m * 3 * * ne nrs ^ P rem °l ar m the upper jaw is almost rudi- 

 mentary, its opposing tooth in the lower jaw is wanting ; in the 

 milk-dentition, however, the first of the three lower molars is repre- 

 sented by an exceedingly small cylindrical tooth. 



Hob. South Africa. 



This species does not appear to occur in the Zulu country. 



I now propose to consider briefly whether the theory of evolution 

 offers any reasonable manner of accounting for the present differen- 

 tiation and distribution of the group. 



I shall first glance at the chief facts bearing upon this question 

 which are afforded by the differentiation and distribution of the 

 Antelopes in general, both in past and present times. I shall then 

 point to the principal deductions which these facts suggest, and shall 

 conclude my remarks by laying before the Society an hypothesis 

 which appears to me to account reasonably for the facts as we now find 

 them. 



In looking back to our earliest knowledge of the Antelopes, which 

 dates from the later Miocene ages, several important facts present 

 themselves. Foremost amongst these is the great fact that the plat- 

 form upon which Antelope life was exhibited in the Miocene and 

 Pliocene periods differed certainly in its extent, and possibly in its 

 entire geographical position, from that upon which we now find the 

 form most richly represented. An examination of the composition of 

 this ancient northern Antelope fauna reveals two striking features : — 

 first, the varied and strong differentiation which had taken place 

 in the form even at this early period ; and, secondly, the fact that 

 mixed with many modifications which have entirely disappeared, 

 were found types identical (speaking broadly) with some of the most 

 important generic forms amongst the exististing Antelope fauna. 

 For instance in the Palceoreas lindermayeri of Wagner we have an 

 animal which may be fairly taken as representing the genera Oreas 

 and Tragelaphus, in the strongly keeled horns more nearly resem- 

 bling the former, in its smaller size and more delicate build the latter 

 genus, while in the form of skull it closely agrees with both the exist- 

 ing genera. 



In the extinct form Palceory.v, the existing Oryx finds a repre- 

 sentative ; in Antilope palceindica (Falconer) all the characteristic 

 features of the skull of Alcelaphus are represented, and in Antilope 

 recticornis (Gervais) those at present peculiar to that oiHippotrayus. 

 Nor is the group at present under consideration unrepresented. 



Differing in structure in only two characters of importance from 

 existing Gazelles, is the Gazella brevicornis of Gaudry, large quanti- 

 ties of the remains of this species having been found by him at Pikermi, 



