the col'jiirs of certain Lcpldoptoui. 439 



The pupae of P. rapes are divided into 11 classes, 

 passing from very dark varieties: — Dark (1), (1), and 

 (2), through the intermediate forms dark (B), (3) and 

 U(j]it (3), into the various shades of light pupae, dark 

 (4), (4), and U(jht (4), and finally into the green pale (5) 

 and deep (5). I need not describe those further, as there 

 are only 7 pupae of this species tabulated below. But 

 the full account will be found in my previous paper [1. c. 

 pp. 410, 411), and 10 of the varieties are figured in the 

 Plate (figs. 32-41, all x 2), as well as 7 of P. hrassicce 

 (figs. 24-30, all X 2). 



In the paper I have just referred to, a number of 

 experiments, with papers of various colours, showed a 

 great susceptibility on the part of these Pieridfe to 

 reflected light within the limits of the orange and yellow. 

 This light prevented the appearance of superficial 

 pigment, and rendered the pupae green. I was most 

 anxious to experiment further with screens of coloured 

 glass. 



Such an investigation was undertaken in the autumn 

 of 1888, nearly mature captured larvae of P. hrassicce 

 and a much smaller number of P. rapce being placed in 

 the cases described below and fed until pupation. Any 

 conclusions from the results are much weakened by the 

 small numbers subjected to the various conditions, and 

 this was due to the excessive mortality of P. hrassicee 

 during 1888 from the attacks of Ichneumons. The pupiB 

 tabulated below are only a fifth of the larvae introduced, 

 424 having died from this cause. 



The pupae were compared in the following spring, 

 April 6. They were removed from the cases and placed 

 side by side on white paper, and very carefully compared 

 when subject to the same conditions of illumination. 



As regards P. hrasaicce, the differences between 1 (a), 

 1 (/3), and 1 (7) were well marked and distinct ; but the 

 various tints of ground-colour, orange, whitish, greenish, 

 and yellowish (represented in the table by the letters 

 o, w, g, and // respectively), found in each of these divi- 

 sions were almost concealed by the predominant grey, 

 so that they constitute features of very little importance, 

 and it is doubtful whether it is necessary to mention 

 them at all. But as the distinction was made at the 

 time, I have repeated it. The greenest pupae, the (3)s, 

 were not transparent-looking like the forms described 



