{and heterogoneiilic) dimorpJiism in AgrimJes ihersites. 311 



the first or spring brood of A . fhersites, although it appeared 

 at much the same date as the second brood lower down. 

 All the specimens of which I had previously examined the 

 androconia belonged to the summer brood ; I had in fact few 

 specimens of the spring brood {i. e. the one that passes the 

 winter as a larva), however, I had some, and, on examining the 

 androconia of one of these, they proved to be of the escheri 

 form of the Belgian and Le Lautaret examples. This 

 made definite and exact my somewhat hazy and imaginative 

 idea that the monogeneutic race corresponded to the spring 

 brood of this digeneutic one. 



This result is remarkable in several aspects. I am not 

 aware of any obvious difference between the specimens of 

 the two broods of A. ihersites. The spring brood is usually 

 smaller, but not markedly so, except in occasional examples, 

 and the summer brood is often small. Yet we have, 

 between the two broods, in this difference in the andro- 

 conia, a difference that is probably of a more profound 

 character than any colour difference of the wing surface, 

 and yet it seems to be the only difference between the 

 broods. 



Another aspect is that these androconia have always 

 been held to be very constant characters, but slightly 

 variable in any species, and therefore trustworthy as 

 marking differences between species. It is, of course, 

 highly probable that many of those who have examined 

 these scales have been satisfied with examining one or two 

 examples of a species, and therefore conclusions, however 

 commonly accepted, are not very trustworthy if founded 

 on so narrow a basis. 



It is also of much interest to find that this new, but 

 probably really much older form of scale so closely resembles 

 those of A. escheri, to which species A. ihersites is more 

 closely allied than to any other, and that neither form 

 of scale associates itself in any way with those of P. 

 icarus. 



In this connection it may be observed that A. escheri 

 is essentially single-brooded. I do not know any place 

 where it is double-brooded, so far as my observation goes, 

 or so far as I can gather from records, though it just pos- 

 sibly is so in some southern localities.* Assuming the 



* Mr. H. Powell tells me he believes it is single -brooded along the 

 Riviera, and so far as he knows everywhere. 



