Chap. VIII. Sexual Selection. 23S 



we do know with respect to the horns of deer, cattle, &c., those 

 of the prong-horned antelope appear at an intermediate period 

 of hfe,— that is, not very early, as in cattle and sheep, nor very 

 late, as in the larger deer and antelopes. The horns of sheej), 

 goats, and cattle, which are well developed in both .sexes, though 

 not qiiito equal in size, can be felt, or even seen, at birth or soon 

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

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

 horned; foi' I cannot find on enquiry,''^ that the horns are 

 developed later in life in this breed than in ordinary sheep in 

 which both sexes are horned. But with domesticated sheep the 

 presence or absence of horns is not a firmly fixed character ; for 

 a certain proportion of the merino ewes bear small horns, and 

 some of the rams are hornless; and in most breeds hornless 

 ewes are occasionally produced. 



Dr. W. Marshall has lately made a special study of the pro- 

 tuberances so common on the heads of birds,'^ and he comes 

 to the following conclusion ; — that with those species in which 

 they are confined to the males, they are developed late in 

 life; whereas with those species in which they are common to 

 the two sexes, they are developed at a very early period. This is 

 certainly a striking confirmation of my two laws of inheritance. 



In most of the species of the splendid family of the Pheasants, 

 the males differ conspicuously from the females, and they acquire 

 their ornaments at a rather late period of life. The eared 

 pheasant (C'n.sxoptilon auritum), however, offers a remarkable 

 exception, for both sexes possess the fine caudal plumes, the 

 large ear-tufts and the crimson velvet about the head ; I find 

 that all these characters appear very early in life in accordance 

 with rule. The adult male can, however, be distinguished from 

 the adult female by the presence of spurs; and conformably 



" I have been assured that the however, a breed of sheep in which, 



horns of the sheep in North Wales as with merinos, the rams alone 



can always be felt, and are some- bear horns ; and Mr. Winwood 



times even an inch in length, at Reade informs me that in one case 



birth. Youatt says (' Cattle,' 1834, observed by him, a young ram. 



p. 277), that the prominence of born on Feb. 10th, first shewed 



the frontal bone in cattle penetrates horns on March 6th, so that in this 



I he cutis at birth, and that the instance, in conformity with rule, 



horny matter is soon formed over the development of the horns oc- 



]j._ curred at a later period oi life than 



" I am greatly indebted to Prof. in Welsh sheep, in which both sexes 



Victor Cams for having made en- are horned. 



■juiries for me, from the highest " ' Ueber die knocheruen Schadel- 



authorities, with respect to the hooker der Vogel ' in the ' Nieder- 



merino sheep of Saxony. On the landischen Aruhiv fur Zoologie,' 



Guinea coast of Africa there is, Baud 1. Heft 2, 1872. 



