Or perhaps the _protection_ is acquired because this tendency exists. I admit therefore in the case of concealed nests they [habits] may have been acquired for protection. Now for the special case. 7. In the very weak-flying Leptalis both sexes mimic Heliconidæ. 8. In the much more powerful Papilio, Pieris, and Diadema it is generally the _female only_ that mimics Danaida. 9. In these cases the females often acquire more bright and varied colours than the male. Sometimes, as in _Pieris pyrrha_, conspicuously so. 10. No single case is known of a male Papilio, Pieris, Diadema (or any other insect?) _alone_ mimicking a Danais, etc. 11. But colour is more frequent in males, and _variations_ always seem ready for purposes of sexual or other selection. 12. The fair inference seems to be that given in proposition 5 of the general argument, viz. that _each species_ and _each sex_ can only be modified by selection just as far as is absolutely necessary, not a step farther. A male, being by structure and habits less exposed to danger and less requiring protection than the female, cannot have more protection given to it by Natural Selection, but a female must have some extra protection to balance the greater danger, and she rapidly acquires it in one way or another. 13. An objection derived from cases like male fish, which seem to require protection, yet having brighter colours, seems to me of no more weight than is that of the existence of many white and unprotected species of Leptalis to Bates's theory of mimicry, that only one or two species of butterflies perfectly resemble leaves, or that the instincts or habits or colours that seem essential to the preservation of one animal are often totally absent in an allied species. * * * * * _Down, Bromley, Kent. September 23, 1868._