422 Mr. F. Merri field and Mr. E. B. Poulton on 



extinction due to the attacks of a single species of parasite 

 is still immense, only about f of the whole surviving it. 



1898. Sept. 



Xuiiiber of (ieaths 



appart'iitly duo to 



other causes. 



20 



18 



29 



3 



71 

 Oct. 1 37 2 



49 

 32 



7 

 17 



5 

 1899 at least 31 at least 20 



Total 273 



6^.— EXPERIMENTS UPON THE PUP^ OF 



Piet'is rapi&. 



1. Experiments upon the Winter Pup^. of 



Ficris rapx-. (F. M.) 



The next experiments tried were on this species and 

 are detailed in the foUowinof section. I was late for this 

 species and did not experiment with more than 50 or 60 

 larvse, from which I obtained the single row of about 

 40 pupse which are now shown in the Exhibition Case. 

 Here I call attention to the contrast between those in 

 the black surroundings on the one hand and those in 

 the green paper, yellow, or orange surroundings on the 

 other, the green in this species seeming more effective than 

 it proved with the other species and the yellow less so. 



2. Results of the above Experiments. (E. B. P.) 



The colour variations of the pupiB of P. rcvprn have been 

 already described and figured (Phil. Trans. 1887, /. c. pp. 

 410, 411, Plate 26, figs. 31—41), and it is here only 

 necessary to state that the standard classification begins 

 with the darkest pup;e (1), ranging througli the less dark 

 (2) and still Hghter (3) to the pale (4) and the green (5). 



Mr. Merrifield's pupa3 were compared on March 20, 

 1899 : the results are given below without much detail. 



