. The descent of man : and selection in relation to sex. Evolution; Natural selection; Heredity; Human beings. Chap. X. Coleoptera. 295 which the sexes differ, are coloured more richly than the males, and'this does not accord with the common rule in regard to colour, when acquired through sexual selection. A most remarkable distinction between the sexes of many beetles is presented by the great horns which rise from the head, thorax, and clypeus of the males; and in some few cases from the under surface of the body. These horns, in the great family of the Lamellicorns, resemble those of variou
. The descent of man : and selection in relation to sex. Evolution; Natural selection; Heredity; Human beings. Chap. X. Coleoptera. 295 which the sexes differ, are coloured more richly than the males, and'this does not accord with the common rule in regard to colour, when acquired through sexual selection. A most remarkable distinction between the sexes of many beetles is presented by the great horns which rise from the head, thorax, and clypeus of the males; and in some few cases from the under surface of the body. These horns, in the great family of the Lamellicorns, resemble those of various quadrupeds, such as stags, rhinoceroses, &c., an-d are wonderful both from their size and diversified shapes. Instead of describing them, I have given figures of the males and females of some of the more re- markable forms. (Figs. 16 to 20.) The females generally ex- liibit rudiments of the horns in the form of small knobs or ridges; but some are destitute of even the slightest rudiment. On the other hand, the horns are nearly as well developed in the female as in the male of Phanceus lancifer; and only a little less well developed in the females of some other species of this genus and of Copris. I am informed by Mr. Bates that the horns do not differ in any manner corresponding with the more important characteristic differences between the several subdivisions of the family: thus within the same section of the genus Onthophagus, there are species which have a single horn, and others which have Fig. 16. Chalcosoma atlas. Upper figure, male (roduced); lower figure, female (nat. size).. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Darwin, Charles, 1809-1882. New York : D. Appleton and Company
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