( cxiv ) 



concentration of the broader band of pupal tissue specially 

 prepared to meet the pressure when it first became a danger. 

 Comparison with the pupae of some of our common British 

 Geometrse supports the hypothesis set forth above ; for it is 

 seen that very similar changes have independently occurred, 

 and occurred so recently that the essential stages are still 

 pieserved. Furthermore, they are invariably met with in 

 species which have a short pupal period passed in the warmer 

 months of the northern year. Eagonia quercinaria spins a 

 loose and open cocoon, within which the chrysalis, as well 

 as the larva befoi-e pupation, develops an effective cryptic 

 colouring.* Both larva and pupa are freely exposed to 

 view through chinks in the scanty network and between 

 the imperfectly united leaves. Uropteryx samhucaria con- 

 structs a slight hanging cocoon, affording very little con- 

 cealment. The enclosed pupa bears a marked cryptic 

 appearance, while the only experiment which has been made 

 indicates the possibility of a well-developed power of individual 

 colour adjustment. t Both these species, and especially the 

 last, have long since reached the stage at which the reduction 

 of the cocoon became advantageous. In the genus Zonosoma 

 {E-phyra) we independently arrive at the same climax of reduc- 

 tion attained in the Pierinse, etc., the cocoon being represented 

 by a supporting loop and the means of fixation of the posterior 

 extremity. | 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 pupa?. The exposed Ephyrid chrysalis 

 is fully as cryptic as that of the average buttei'fly, 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.§ 



* Trans. Eut. Soc. Lond., 1885, \^. 319. 



t See "Colours of Animals," Loudon, 1890, pp. Ill, 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. 



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



§ Trans. Ent. Soc. Lond., 1884, p. 51 ; Phil. Trans. Koy. Soc, vol. 

 178 (1887), B., pp. 437, 438. 



