338 BRITISH BUTTERFLIES. 



are much more easily seen than in the type, and, perhaps, that the 

 blue spots are the rule, rather than, as elsewhere, the exception. 

 Beneath, however, the black spots of the underwings, and the orange 

 marginal line, are pronounced in a way that no other form approaches. 

 Staudinger calls this hypophlaeas, Boisd., and says that it is identical 

 with the American form. Though Scudder regards the American form 

 as abundantly distinct from the European, he does not appear to have 

 been aware of the identity of the Lapland form with the American 

 (some of the specimens exhibited agree exactly with his description of 

 the American form), whilst it is difficult to regard the Lapland form as 

 distinct from our ordinary form, though we possess no specimens from 

 intermediate districts to show the gradation. Chapman is not quite 

 sure, but thinks the "warm" varieties have the underside of the hind- 

 wing distinctly of more uniform tint and freer from spots and orange 

 marginal line than the type. He mentions that Merrifield has shown 

 that the effect of a high temperature in producing dark specimens of 

 phlaeas, takes place during the pupal stage, whilst the imago is maturing 

 within it, and that warmth in an earlier pupal, and in the larval, stage, 

 has little or no effect. He adds that " we speak of the difference between 

 phlaeas and eleus as a seasonal one, but this is not strictly correct. 

 It is an individual change due to the direct action of temperature, 

 there is no distinct alternation of forms as in Araschnia levana and 

 prorsa, or as in our English Ennomids, alternations which Merrifield 

 found he could break through only with difficulty. In R. phlaeas each 

 individual is prepared, up to the pupal stage, to take either form. How 

 then, he asks, may we arrange the ordinary (i.e., not aberrational) forms 

 of phlaeas (west European) ? We may, with little hesitation, accept 

 hypophlaeas as a distinct geographical race or subspecies. When we 

 come to eleus, we must, I think, in the first place use the name in two 

 senses ; it is primarily the name of the darkest form of phlaeas. It 

 must also be given to the southern race of phlaeas. The experiments of 

 Weismann, Merrifield, Standfuss, Fischer, etc., bring out apparently, 

 that the southern races respond with much greater readiness to the 

 proper temperature stimulus that produces eleus, than the central 

 European form does. There also exists a belief that the normal (cool) 

 form of this southern race is darker than central European R. phlaeas. 

 In some cases this is probably true. Whether essentially darker, or 

 merely responding more easily to stimuli to become darker, it has a 

 sufficiently different constitution to be recognisable as a race, though 

 not, perhaps, so definitely a subspecies as we may take hi/pophlaeas 

 to be. The name of this southern subspecies would necessarily be 

 eleus. We cannot but recognise, however, that English phlaeas can 

 provide eleus, and very commonly takes the transitional form of sitffusa, 

 Tutt, whilst specimens exhibited demonstrate that, to the south of 

 the Alps and in Spain, the race eleus can produce tolerably typical 

 examples of phlaeas. We have then : 



Ruvdcia phlaeas, phlaeas f .t. phlaeas | „ , , ,-, 



r ' r r , [Central Europe. 



,, eleus j * 



,, ,, eleus ,. phlaeas) .. ,, ,, 



S ]■ bouth Europe. 



,, eleus j * 



,, phlaeas, hypophlaeas Lapland. 



It must also be recognised that eleus, besides such transitional forms 

 as suffusa, presents a large, dark, suffused form, and a smaller, 



