266 THE DESCENT OF MAN. 



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 f 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 

 protuberances so common on the heads of birds, J 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 



* 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 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. 



f I am greatly indebted to Prof. Victor Carus 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 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 showed horns 

 on March 6th, so that in this instance, in conformity with rule, the 

 development of the horns occurred at a later period of life than in 

 Welsh sheep, in which both sexes are horned. 



J " Ueber die kno'chermen Schadelho'cker der Vflgel " in the " Nie- 

 derlandischen Archiv. filr Zoologie," Band I, Heft 2, 1872. 



