Archive image from page 23 of The descent of man, and. The descent of man, and selection in relation to sex descentofmansele187302darw Year: 1873 Fig. 29.—Xiphophorus Hellerii. Upper figure, male; lower figure, female. In a siluroid fish, inhabiting the fresh waters of South America, namely the JPlecostomus barbatus 16 (Fig. 30), the male has its mouth and interoperculum fringed with a beard of stiff hairs, of which the female shows hardly a trace. These hairs are of the nature of scales. In another species of the same genus, soft flexible tentacles project from the front part of the head of
Archive image from page 23 of The descent of man, and. The descent of man, and selection in relation to sex descentofmansele187302darw Year: 1873 Fig. 29.—Xiphophorus Hellerii. Upper figure, male; lower figure, female. In a siluroid fish, inhabiting the fresh waters of South America, namely the JPlecostomus barbatus 16 (Fig. 30), the male has its mouth and interoperculum fringed with a beard of stiff hairs, of which the female shows hardly a trace. These hairs are of the nature of scales. In another species of the same genus, soft flexible tentacles project from the front part of the head of the male, which are absent in the female. These tentacles are prolongations of the true skin, and therefore are not homologous with the stiff hairs of the former species; but it can hardly be doubted that both serve the same purpose. What this purpose may be it is difficult to conjecture; ornament does not here seem probable, but we can hardly suppose 15 Dr. Giinther makes this remark: ' Catalogue of Fishes in the Brit- ish Museum,1 vol. iii. 1861, p. 141. 16 See Dr. Giinther oivthis genus, in 'Proc. Zoolog. Soc.' 1868, p. 232.
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