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MAMMALIA ALBERT GŰNTHER, M.A., M.D., PH.D., F.R.S.

THE GENERAL SUBJECT. α. Separate Publication.

DARWIN, C. The Descent of Man, and Selection in relation to Sex.

London: 1871. 16mo, vol. i. pp. 423, vol. ii. pp. 475, illustrated by numerous woodcuts.

As is indicated by the title, this work consists of two parts, the second of which comes within the scope of the 'Zoological Record;' and here we have particularly to refer to chapters 17 and 18, in which the secondary sexual characters of Mammals are discussed. The main theory of sexual selection depends upon the fact that there is a struggle among the males for the possession of the females - a struggle carried on either by actual fighting or by rivalry in various charms, as odour, voice, or beauty. Among Mammalia the law of battle appears to prevail throughout; and the greater size, strength, courage, and pugnacity of the male, his special weapons of offence, as well as his special means of defence, have all been acquired or modified through sexual selection. Likewise the odoriferous glands and the ornamentations of the integuments have been developed in the male through the same cause; but whether, in Mammals, the same view can be extended to the voice, is doubtful. The law of the equal transmission of characters to both sexes, as far as

1871. [vol. VIII.]

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colour and other ornaments are concerned, has prevailed far more extensively with Mammals than with Birds; but in regard to weapons, these have often been transmitted either exclusively in a much higher degree to the males than to the females. Their absence in the female can be accounted for only by the form of inheritance which has prevailed. The contest between the individuals of the same sex, whether peaceful or bloody, has, with the rarest exceptions, been confined to the males; so that these have been modified through sexual selection, either for fighting with each other or for alluring the opposite sex, far more commonly than the females.

A large portion of' the animal kingdom is passed in review, as regards sexual differences and the means by which this differentiation has been produced. This part abounds in matter of interest; and we may well believe that it required many years to collect these materials. The account of the sexual differences in Mammals occupies pages 239-315 of the second volume, and is illustrated by numerous excellent woodcuts.

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REPTILIA BY ALBERT GŰNTHER, M.A., M.D., OH.D., F.R.S.

THE GENERAL SUBJECTS. NOTES AND FAUNÆ.

DARWIN, C. The Descent of Man, and Selection in relation to Sex.

London: 1871. 16mo, vol. i. pp. 423, vol. ii. pp. 475, with numerous woodcuts.

Part of chapter xii. (pp. 24-37) contains the most complete account of the secondary sexual characters of Reptiles and Amphibians that has ever been published. We shall refer in the special part of this Record to some of the facts which are not generally known, or which have been illustrated by Mr. Darwin. The author comes to the conclusion that sexual selection seems to have played almost as important a part among Reptiles as among Birds. But the less conspicuous colours of the females, in. comparison with those of the males, cannot be accounted for, as in the case of birds, by the exposure of the females to danger during incubation. [Cf. suprà, pp. I, 2, 25- 27.]

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PISCES BY ALBERT GŰNTHER, M.A., M.D., OH.D., F.R.S.

DARWIN, C. The Descent of Man, and Selection in relation to Sex.

London: 1871. 16mo, vol. i. pp. 423, vol. ii. pp. 475, with Numerous woodcuts.

Part of chapter xii. (pp. 1-24) contains an account of the best-authenticated cases of sexual differentiation in fishes, some of which will be referred to in the special part of this Record.

(Cf. suprà, pp. 1, 2, 25-27) 77.)