102 [May, 



ON THE LARVJE, HABITS, AND STRUCTURE OF LITHOCOLLETIS 

 CONCOMITELLA, Bankes, AND ITS NEAREST ALLIES. 



BY JOHN H. WOOD, M. B. 

 {Concluded from page 75). 



BIOLOGICAL ASPECTS. 



Perhaps I may be allowed to look for a moment at some of the 

 biological aspects of the appendages, those remarkable organs of the 

 male insect. The point that first strikes one is their extraordinary 

 variety, which is the more remarkable, since being organs of prehen- 

 sion, endowed with a clear and very definite function, it might have 

 been expected that they would have been moulded, like the legs or 

 wings, in a comparatively limited number of forms, each form being 

 common to many individual species. This, however, is totally at 

 variance with the reality ; indeed, in very few species are the organs 

 exactly alike, whilst the departures are often so sudden and violent 

 that among the members of some of the large genera one never knows 

 what to expect. It will be said, and I think the impression is a 

 general one, that this exuberance of variation is connected with a 

 similar variation in the other sex, and that there is a mutual relation- 

 ship between them, the object of which is to prevent unnatural 

 unions. But I doubt it. Insects stand too high in the scale to need 

 so mechanical a restraint ; besides, there is abundant proof that they 

 are guided and controlled in the matter by their senses, much as are 

 the higher animals. For let this directing sense be at fault — obscured 

 it may be by the collector's treacle, or confused by the well-known 

 device for procuring hybrids, and unnatural unions occur readily 

 enough, mechanical impedimenta notwithstanding. 



The facts, too, are opposed to any such correspondence between 

 the parts in the two sexes. Let me take an example from the genus 

 Sciaphila: — in this genus there are two well-known forms of the 

 female abdomen, one in which the end is broad and blunt, the other 

 in which it is fine and pointed, but no two equivalent forms are to be 

 found in the other sex, so that a grouping of the species founded on 

 the parts of the female would not agree with one founded on those of 

 the male. So far as my own investigations have gone, the state of 

 things is as follows : — ^in suhjectana, virgaureana, pascuana, and chry- 

 santhemana the male appendages are all much alike, though each 

 differs from the others in a slight and about equal degree, yet the 

 female abdomen of suhjectana is fine-ended, while in the three other 

 species it is blunt-ended. The male of sinuana on the other hand is 



