( clxxiii ) 



and courts a mate : it is the ? only which oviposits, nidificates, 

 and procures and stores food (animal or vegetable) for its young. 

 So it seems quite natural that the sexual modifications of $ 

 structures should point as a ri;le to pairing, and those of the 

 $ to the duties which are subsequent to it. 



(3) Protection of the individual (e. g. Cryptic and Aposematic 

 Coloration, etc.) seems to account for a few, but only a very 

 few, of the strictly sexual characters of Aculeates. Wallace 

 appears to go further than this, and to imply that in this 

 group there is no need and no development of protective 

 characters at all ; for he remarks that "the two sexes of the 

 stinging Hymenoptera are equally well coloured," * and, again, 

 that " there is not a single instance recorded in which any one 

 of them is coloured so as to resemble a vegetable or inanimate 

 substance." "j" Neither of these statements, as it seems to me, 

 and as I shall presently try to show, is true without exception. 

 But the exceptions (at any rate as far as Sexual characters 

 are concerned) are undoubtedly few ; though one at least, 

 which I shall discuss later, appears to me both certain and 

 striking. 



(4) Kot only in their apparent purpose, but in several other 

 respects, the secondary sexual modifications of structure of 

 Aculeate $$ differ remarkably, as it seems to me, from those 

 observable in $ $ of the same group. 



They differ (a) in being more diversified, less restricted to 

 particular parts of the body, and more various in themselves : 

 (5) in being more paradoxical, i. e. departing further from the 

 normal characters of the group : (c) in being more sporadic, 

 i. e. appearing (so to speak) suddenly, here a.id there, in 

 particular species or small groups, and often (when they occur 

 similarly in more cases than one) shared by this or that 

 species, not with its nearest congeners, but with insects much 

 more distantly related to it ; whereas characters distinctive of 

 females generally run more or less uniformly and continuously 

 through whole genera or even larger groups, and are very 

 seldom peculiar to the $ $ of a single species : (d) in being for 

 the most part altogether unrepresented in the other sex ; whereas 

 $ characters are mostly little more than augmentations of some 

 * On Natural Selection, p. 114. j Ihid., p. 72. 



