Page:Descent of Man 1875.djvu/250

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234
The Descent of Man.
Part II.

would lead to their development 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, twelve or even more months in the stags of the six other and larger species.[1] 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 likewise common to both sexes in this one species alone.

In several kinds of antelopes, only the males are provided with horns, whilst in the greater number both sexes bear horns. With respect to the period of development, Mr. Blyth informs me that there was at one time in the Zoological Gardens a young koodoo (Ant. strepsiceros), of which the males alone are horned, and also the young of a closely-allied species, the eland (Ant. oreas), in which 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; whilst 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,[2] 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

  1. 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 have to thank Mr. Eyton and others for information. For the Cervus alces of N. America, see 'Land and Water,' 1868, pp. 221 and 254; and for the C. Virginianus and strongyloceros of the same continent, see J. D. Caton, in 'Ottawa Acad. of Nat. Sc.' 1868, p. 13. For Cervus Eldi of Pegu, see Lieut. Beavan, 'Proc. Zoolog. Soc.' 1867, p. 762.
  2. Antilocapra Americana. I have to thank Dr. Canfield 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.