SEXUAL SELECTION 309 



both sexes are horned. Now it is in strict conformity with 

 our rule, that in the young male koodoo, although ten 

 months old, the horns were remarkably small, considering 

 the size ultimately attained by them ; while in the young 

 male eland, although only three months old, the horns were 

 already very much larger than in the koodoo. It is also 

 a noticeable fact that in the prong-horned antelope," only a 

 few of the females, about one in five, have horns, and these 

 are in a rudimentary state, though sometimes above four 

 inches long; so that, as far as concerns the possession of 

 horns by the males alone, this species is in an intermediate 

 condition, and the horns do not appear until about five or 

 six months after birth. Therefore, in comparison with what 

 little we know of the development of the horns in other 

 antelopes, and from what we do know with respect to the 

 horns of deer, cattle, etc., those of the prong-horned antelope 

 appear at an intermediate period of life — that is, not very 

 early, as in cattle and sheep, nor very late, as in the larger 

 deer and antelopes. The horns of sheep, goats, and cattle, 

 which are well developed in both sexes, though not quite 

 equal in size, can be felt, or even seen, at birth or soon 

 afterward.*' Our rule, however, seems to fail in some breeds 

 of sheep, for instance, merinos, in which the rams alone are 

 horned; for I cannot find on inquiry" that the horns are 

 developed later in life in this breed than in ordinary sheep 

 in which both sexes are horned. But with domesticated 



*• AniUocapra Americana. I have to thank Dr. Canfleld for information 

 with respect to the horns of the female: see also his paper in "Proc. Zoolog, 

 Soc," 1866, p. 109. Also Owen, "Anatomy of Vertebrates," vol. iii. p. 627. 



■*' I have been assured that the horns of the sheep in North Wales can 

 always be felt, and are sometimes even an inch in length, at birth. Youatt 

 Bays ("Cattle," 1834, p. 271), that the prominence of the frontal bone in cattle 

 penelxates the cutis at birth, and that the horny matter is soon formed over it. 



■" I am greatly indebted to Prof. Victor Carua for having made inquiries for 

 me, from the highest authorities, with respect to the merino sheep of Saxony. 

 On the Guinea coast of Africa there is, however, a breed of sheep in which, 

 as wlUi merinos, the rams alone bear horns; and Mr. Win wood Beade informs 

 me that in one case observed by him a young ram, bom on Feb. 10, first showed 

 horns on March 6, so that in this instance, in conformity with rule, the develop- 

 ment of the horns occurred at a later period of life than in Welsh sheep, ia 

 wbich both sexes are homed. 



