150 INSECTS AND HEREDITY 



colouring. 1 Both larva and pupa are freely exposed to 

 view through chinks in the scanty network and between 

 the imperfectly united leaves. Uropteryx sambucaria (the 

 1 Swallow-tailed Moth ') constructs a slight hanging cocoon, 

 affording very little concealment. The enclosed pupa 

 bears a marked cryptic appearance, while the only experi- 

 ment which has been made indicates the possibility of a 

 well-developed power of individual colour adjustment.' 2 

 Both these species, and especially the last, have long since 

 reached the stag-e at which the reduction of the cocoon 

 became advantageous. In the genus Zonosoma (Ephyra) 

 we independently arrive at the same climax of reduction 

 attained in the Pierinae, &c., the cocoon being repre- 

 sented by a supporting loop and the means of fixation of 

 the posterior extremity. 3 No search has been made, so 

 far as I am aware, for a special strengthening of the 

 cuticle upon which the loop presses, but it is probable 

 that nothing of the kind is required by these small light 

 pupae. The exposed Ephyrid chrysalis is fully as cryptic 

 as that of the average butterfly, but it lacks the power of 

 colour adjustment. When the Ephyrid larva is dimorphic, 

 green or brown, the colour of the pupa corresponds 

 to that of the larva from which it developed. 4 Such 

 correspondence has not been observed in any other 

 Lepidopterous insect. 



If we take into account the fact that Zonosoma (Ephyra) 

 is a characteristic Geometrid genus, although its method of 

 pupal suspension is unique in a family whose species make 

 cocoons or bury, we may feel confident that it has been 

 descended from cocoon-making ancestors, and that Euoo- 

 nia quercinaria and Uropteryx sambucaria give us a clear 

 idea of the steps by which the reduction was effected. 



1 Trans. Ent. Soc. Lond., 1885, p. 319. 



s See Colours of Animals, London, 1890, pp. in, 112. Only one 

 example was placed on white paper before pupation. Although the 

 resulting chrysalis was very pale and strikingly different from the ordinary 

 appearance, the evidence is quite insufficient, and it is much to be hoped 

 that the experiment will be repeated upon a large scale. 



3 Trans. Ent. Soc. Lond., 1884, p. 57. 



4 Trans. Ent. Soc. Lond., 1884, p. 51 ; Phil. Trans. Roy. Soc, vol. 178 

 (1887), B., pp. 437. 438. 



