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Show 18 HEXUAL SELECTIO~. PAII'l' IL. tulmiL that ttDV animal has Lecn made conspicuous as ~n ai<l to its ow~ destruction. It is possiLle that em-tam fi h 'S may have been rendered conspic~ous in order to Yfarn birds and beasts of prey (n.s explame<l when trea~ino · of caterpillars) that they wore unpalatable; l>ut 1t is 710t I believe, known that any fish, at least any fresh'"< ttcr' fish, i · rejected from being distasteful to fi hdovouring animals. On tho whole, the most proLablo view in ron·arcl to ·tho fishes, of which both sexes arc brilliantly 0 coloured, is that their colours have been acquired by the males as a sexual ornament, and have Lc n transferred in an equal or nearly equal degree to tho other sex. \Yo haYO now to consider whether, when the malo differs in a marked manner from tho female in colour or in other ornaments, he alone bas been modified, with tlw variations inherited only by his male off.-;pring; or whether the female has been specially modified aml 1·endered inconspicuous for tho sake of protection, such modifications being inherited only by the females. It it> impossible to douLt that colour has been acquired by many fi hes as a protection: no one can behol<l the speekled upper surface of a flounder, and overlook its. resemblance to the sandy bed of the sea on which it liYcs. One of the most striking instances ever recorded of an animal gaining protection by its colour (as far as can be judged in preserved specimens) and by its form, is thai given by Dr. Gunther 29 of a pipefish, which, with its redd.ish streaming filaments, is har lly distinguishable from tho sea-weed to which it clings with its prehensile tail. But the question now under consideration is whether the females alone have been modified for this object. Fishes offer valuable ::Ol 'Proe. 7.oolog. Soc.' 1 u5, p. 327, pl. xiv. nncl XV. CHAP. XIL FISHE8. 1!1 evidence on this bead. We can see that one sex will not Le mocJified through natural selection for the sake of protection more than the other, supposing both to vary, nnloss one sox is exposed for a longer period to danger, or haH less power of escaping from such d~nger than the other sex; and it cloPs not appear that With fishes the sexes differ in these respects. As far aR there is any ?iffcrence, the males, from being generally of smaller SIJ~e, and from wandering more about, an' exposed to greate_r danger than the females ; and yet, when the sexes differ, the males are almost always the most conspicuously colomed. The ova are fertilised immediately after being deposited, and when this proce ·s lasts for se-veral day~, as in the case of the salmon, ~u the female, during the whole time.. is attended Ly tho male. After the ova are fertilised they are, iu most cases, left unprotected by both parents, so that the males and females, as far as oviposition is concerned ~re equally exposed to danger, and both are cquall; 1mportant for the pr?duction of fertile ova; consequently the more or less br1ghtly-coloured individuals of either se~ would be equally liable to be destroyed or preserved, and b?th would have an equal influence on the colours of the1r offspring or the race. Certain fishes, belonging to several families, make nests ; and some of these fishes take care of their ~oung when _hatched. Both sexes of the brightlyco~ ou~·ed C?·e.ndabrus ~nassa and melops work together in bmldmg their nests With sea-weed, shells, &c.:J1 But the males of certain fishes do all the work and afterward take exclusive charge of the young. This is the case ;:: 1 Ynrr~ll? 'British Fishes,' v~l. ii. p. 11. A?~onlmg t? the obsbrvn.tLOns of 1\i. Gerbc; .·cc Giinther'l:i 'Record of Zoolog. L1terature,' 1865, p. 104. c 2 |