Chap. VIII. 



Sexual Selection. 



235 



we do know with respect to the horns of deer, cattle, &c, tho3e 

 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 develojDed in both sexes, though 

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

 afterwards. 41 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 enquiry, 42 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, 43 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 (Cr<SH<ptihn uuriturn), 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 



41 I have been assured that the 

 horns of the sheep in North Wales 

 can always be felt, and are some- 

 times even an inch id length, at 

 birth. Youatt says (' Cattle,' 1834, 

 p. 277), that the prominence of 

 the frontal bone in cattle penetrates 

 the cutis at birth, and that the 

 horny matter is soon formed over 

 it. 



42 I am greatly indebted to Prof. 

 Victor Cams for having made en- 

 quiries 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 with merinos, the rams alone 

 bear horns ; and Mr. Winwood 

 Reade informs me that in one case 

 observed by him, a young ram, 

 born on Feb. 10th, first shewed 

 horns "on March 6th, so that in this 

 instance, in conformity with rule, 

 the development of the horns oc- 

 curred at a later period o\ life than 

 in Welsh sheep, in which both sexes 

 are horned. 



43 ' Ueber die knochernen. Seh'adel- 

 hocker der Vogel' in the ' Nieder- 

 landischen Archiv fur Zoologie,' 

 Band I. Heft 2, 1872. 



