57 



known that the ovum of CJirysophanus dispar, var. rutilus, has 

 sometimes six and sometimes seven large ribs. I have 

 dissected out both forms from the body of the same female. 



When we come to consider the larva, it is quite easy to 

 see that the special conditions under which each species 

 passes its larval existence must sooner or later exercise a 

 modifying influence on, at least, the external appearance. 

 It seems also that such an influence may be felt and 

 responded to by a larva without producing any effect on the 

 imago. Take, for instance, the two forrns of the larva of 

 A crony eta leporina, the green form, more often attached to 

 alder, and the yellow form, usually feeding on birch. 



Dr. Chapman has described these two forms (" Ent. Rec," 

 vol. iii, pp. 25 and 29), and states that imagines reared from 

 one form will pair readily with those bred from the other 

 form. 



The larva of Cemiostoma laburnella, which lives in a flat 

 mine in the leaves of laburnum, is an ordinary-looking leaf- 

 miner, but the larva of C. spartifolidla, which lives in a 

 gallery under the bark of the twigs of broom, is very peculiar 

 in appearance, being very elongate. The moths produced 

 by these two larvae are so much alike, however, that entomo- 

 logists at present separate them only by one slight character. 

 The Nyniphalidce supply many cases of peculiar larval deve- 

 lopment, such as the strange larvae of Cliaraxes jasius and 

 Apainra iris ("Proceedings," 1907-8, PI. IV), also the larvae 

 of Vanessids and Argynnids with their thorn-like structures. 

 Among the butterflies, too, we find the very highly developed 

 larvae of the genus Chrysophanus, so well adapted to their 

 surroundings. Among the moths there is the genus Chcero- 

 campa, having larvae with eye-like spots and retractile seg- 

 ments, the strange larva of Stauropns fagi and the larvae of 

 Hoplitis milhauseri, Acronycta alni, and Euclidia mi, as well 

 as all the curious larvae of the Geometridce. 



All these appear to be instances of purely larval evolution, 

 brought about by the various conditions under which each 

 species has been obliged to carry on its larval existence. On 

 the other hand many larvae of the Tortricidce which have 

 similar habits, living between leaves spun together, are 

 extremely similar in appearance, but give rise to moths 

 differently marked and coloured, which we recognise as 

 different species. From this we may infer that the con- 

 ditions of larval life, remaining more or less the same, have 

 allowed the larvae to continue their existence without causing 

 any essential change in their outward appearance, although 



