RUMICIA PHLiEAS. 331 



ence observable in the species is that observed in the structure of the 

 front legs throughout the family. There is, however, a marked 

 difference in the general build of the sexes, in the shape of the wings, 

 and in the general brilliancy of the colouring, the $ having more 

 pointed, the 2 more rounded or squared, wings ; the $ also being more 

 prone to darkening of the ground colour, the 2 to a clearer and more 

 brilliant tint, whilst the spots in the latter sex usually occupy a less 

 proportion of the wing (see also postea p. 337). 



Variation. — The variation of Rumicia phlaeas is one of the most 

 difficult subjects of which we have to treat. In the colour, one finds 

 an enormous amount of variation, extending in the one direction to the 

 change of the coppery-red ground colour to white, in the other direction 

 to its suffusion with black to such an extent that some extreme speci- 

 mens may, without exaggeration, be termed black. The aberration 

 with the white ground colour, ab. schmidtii, is of occasional occurrence 

 throughout the greater part of its range, being apparently most rare in ex- 

 treme northern and southern localities, but the difference in the brilliancy 

 of the coppery-red tint is largely a matter of geographical range, coupled 

 with the season of emergence, as is also the strong suffusion shown in 

 the darkest examples. In central Europe, for example, the specimens 

 of the spring brood are bright coppery-red, so also are most of the 

 summer examples, with, however, a strong tendency, in some, to 

 suffusion, especially in hot seasons." In the northern parts of its range 

 the coppery-red, although hardly so intense, is even lighter than the 

 spring broods of the central area. In the southern and eastern parts 

 of its area the specimens of the spring brood are bright, like those of 

 the summer brood of the central area, but a large percentage of the 

 examples of the summer broods are deeply suffused with black, often, 

 in addition, with a distinct tail to the hindwings. This form is known 

 as ab. (et var.) eleus. That these forms are really largely a result of 

 temperature has been, to a great extent, proved by the experiments of 

 Weismann and Merrifield, which may be here noted at length. In 

 1888, specimens of R. phlaeas were captured in the neighbourhood of 

 Camaldoli, near Naples, and laid an abundance of eggs, of which some 

 were reared at Naples by Schiemenz, others at Freiburg by Weis- 

 mann. 



(1) The Neapolitan eggs reared at Naples. — These were laid, in early 

 May, on Faimex acetosella ; the larvse were fed up on this plant, and 

 produced 36 butterflies between June 26th and 29th. These are all 

 characterised by a very broad, deep, black margin on the upperside of 

 the forewings, and by very large, deep, black spots; many also exhibit 

 the black powdering of the brilliant red-golden ground colour charac- 

 teristic of the var. eleus, but the latter character is very unstable, and 

 very unequally developed. Three degrees may be separated, according 

 to the extent of the black powdering on the forewings, as follows : — 



a. Darkest form : — Only three to five small washed-out spots remain of the 

 red-gold of the ground colour ; all the rest of the surface of the wings is powdered 

 with deep black, and only exhibits scattered red-golden scales, which produce a 

 slight golden lustre. Only slight traces of red-golden spots can be recognised 

 outside the band of black spots. Eight specimens of this form. 



/3. Intermediate form :• — The red-golden ground colour is visible outside the 

 band of black spots in the form of definite spots, but all the lower half of the wing 

 is strongly powdered with black. Twelve specimens of this form. 



y. Brightest form : — The lower half of the wing, from the base to the band of 



