markut(/s and attitudes of lepidopterous larvcs. 319 



which found suitable places for pupation in damper and 

 greener situations. I did not then know any instance of 

 protection by a change of colour in the reverse direction. 

 I am now able to supply such an instance. During the 

 present summer (1884) I bred a number of the larvse of 

 Ennomos angularia. The adult larva is dark brown in 

 colour, and in this respect, as well as by its attitude, is 

 extremely well protected by resemblance to the dark 

 twigs of its food-plant (elm). The pupal period is very 

 short, and passed in the hottest part of summer, and 

 the cocoon is very loosely constructed of leaves, between 

 which the larva and subsequently the pupa are generally 

 visible. In this case the brown colour of the larva is 

 discharged before pupation, and it becomes green (see 

 fig. 19, natural size, Plate VII.), and is therefore well 

 protected in its new surroundings. The pupa is also 

 green, but is dimorphic, one form being light bluish 

 green covered with white dots, and the other dark 

 Jbrownish green sprinkled with black dots (see figs. 20 

 and 21, natural size, Plate VII.). Both forms are well 

 protected in the cocoon, and it is probable that the 

 dimorphism is of direct value (see my paper quoted 

 above for other instances of the direct value of 

 dimorphism). In S. illimaria the larva only becomes 

 green over a small part of its surface, and the pupa is 

 of the ordinary shining reddish brown colour, but the 

 cocoon is fairly complete, so that the contents are 

 hidden. I may also add to the instances adduced last 

 year the case of M. stellatarum feeding on G<dium verimi 

 in dry situations exposed to the sun, which darkens very 

 completely all over before pupation, and which wanders 

 over the earth before making a slight cocoon, within 

 which it may be sometimes visible. Again, there is 

 the unusual darkening of the larva of LK rhndd, which 

 makes its cocoon on the bark ; while other larvse {S. 

 poindi and ocellatm), with the same food, darken very 

 slightly, but pupate in the earth, which is covered with 

 green vegetation beneath such trees (growing in moist 

 places). Of course there will remain a great many 

 larvffi which do not gain protection in this way, for 

 example, all those which form complete cocoons at once 

 or bury without wandering and exposing themselves in 

 new surroundings with which their colours do not 

 harmonise. I only urge that certain larvae gain pro- 

 tection by making use (through natural selection) of the 



