Archive image from page 23 of The descent of man, and. The descent of man, and selection in relation to sex descentofmansel02darw Year: 1871 10 SEXUAL SELECTION [Part IL strictly oomparccl with tliosc which aro so frequent with galhnaceous birds.'' > /y Fig. 29.âXiphophoras Hellerii. Upper figure, male; lower flgufe. female. In a sihiroid fish, inhabiting the fresh waters of South America, namely the Plecostomus harhatus ' (Fig. 30), the male has its mouth and interopcrculum fringed with a beard of stiff hairs, of which the female shows hardly a trace. These hairs are of the nature of s
Archive image from page 23 of The descent of man, and. The descent of man, and selection in relation to sex descentofmansel02darw Year: 1871 10 SEXUAL SELECTION [Part IL strictly oomparccl with tliosc which aro so frequent with galhnaceous birds.'' > /y Fig. 29.âXiphophoras Hellerii. Upper figure, male; lower flgufe. female. In a sihiroid fish, inhabiting the fresh waters of South America, namely the Plecostomus harhatus ' (Fig. 30), the male has its mouth and interopcrculum 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 â the stiflf 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 ' Dr. Giinthcr makes this remark: 'Catalogue of Fishes in the Brit- ish Museum,' vol. iii. 1861, p. 141. ' See Dr. Giinthcr on this genus, in ' Proc. Zoolog. Soc.' 1868, p. 232.
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