288 
THE PRINCIPLES OF 
Part II. 
An excellent case for investigation is afforded by the 
Deer Family. In all the species, excepting one, the 
horns are developed in the male alone, though certainly 
transmitted through the female, and capable of occasional 
abnormal development in her. In the reindeer, on the 
other hand, the female is provided with horns ; so that 
in this species, the horns ought, according to our rule, 
to appear early in life, long before the two sexes had 
arrived at maturity and had come to differ much in 
constitution. In all the other species of deer the horns 
ought to appear later in life, leading to their develop- 
ment in that sex alone, in which they first appeared 
in the progenitor of the whole Family. Now in seven 
species, belonging to distinct sections of the family and 
inhabiting different regions, in which the stags alone 
bear horns, I find that the horns first appear at periods 
varying from nine months after birth in the roebuck to 
ten or twelve or even more months in the stags of the 
six other larger species . 24 But with the reindeer the 
case is widely different, for as I hear from Prof. Nilsson, 
who kindly made special enquiries for me in Lapland, 
the horns appear in the young animals within four or 
five weeks after birth, and at the same time in both 
sexes. So that here we have a structure, developed at 
a most unusually early age in one species of the family, 
and common to both sexes in this one species. 
In several kinds of antelopes the males alone are 
24 I am much obliged to Mr. Cupples for having made enquiries for 
me in regard to the Roebuck and Red Deer of Scotland from Mr. 
Robertson, the experienced head-forester to the Marquis of Breadalbane. 
In regard to Fallow-deer, I am obliged to Mr. Eyton and others for 
information. For the Cervus aloes of N. America, see 4 Land and Water/ 
1868, p. 221 and 251; and for the G. Virginianus and strong ylocer os of 
the same continent, see J. D. Caton, in 4 Ottawa Acad, of Nat. Sc/ 
1868, p. 18. For Cervus Eldi of Pegu, see Lieut. Beavan, 4 Proc. 
Zoolog. Soc/ 1867, p. 762. 
