in Pc.dhjri'e ]^[()th-])ree(li)ui. 93 



females, on the following dates: Sept. 27 (2), 30, Oct. 3, 

 7, 8, 14, 16, 19. The one which emerged 8th October 

 was accidentally destroyed, the remaining 8 (exhibited) 

 are of the same general colouring, which seems to be 

 intermediate between the spring and summer colouring, 

 and differs most materially from that of the 2 which 

 emerged in July. The later ones of the 8 are much 

 darker than the earlier ones, and, though the progressive 

 darkening is not quite regular, it is diiiicult to look at 

 them without thinking that retardation of development 

 has been the operative cause, the retardation in this case 

 not being associated with cold, as the pupae have rarely 

 or never been at a loAver temperature than 60° [There 

 are some other facts which rather favour the view that 

 retardation without cold ma.y l)e a cause of, or at least 

 be associated with, darkening. Thus the numerous 

 specimens I have preserved of illunaria show that where 

 one or more of a brood have emerged several days after 

 the rest they are often in a marked degree different in 

 colour, generally darker. And a sleeved female illustraria 

 of the summer emergence of 1888 before mentioned, 

 which was rather liehind the others in feeding up and 

 was not forced at the end, and which, instead of corre- 

 sponding with the average period of about 13^ days (of 

 which 3^ forced) remained from 20 to 22 days in pupa, 

 makes as near an approach in general hue to the spring 

 emergence as do the iced ones of that brood.] 



Simultaneously with the offspring of the forced illas- 

 traria of the 1887 summer emergence, I brought up some 

 29 in a bottle at the ordinary indoor temperature, and 

 the pupse remained at the same. They showed no 

 tendency to split up, but, of the 20 that spun up, all did 

 so between r2th September and 5th October. Ten were 

 on 27th November put out-of-doors, and were brought in 

 1st January, and, after being gradually warmed, were on 

 9th January placed in the forcing-box, and kept there at 

 65° — 70°. These straggled greatly in their emergence, 

 viz., Jan. 28, Feb. 13, 14, 15, 16 (2), 17, 23 (2), and 28 ; 

 5 others, without being frosted, were on 29th January 

 placed in the forcing-box ; these emerged Feb. 9 (3) 

 and Feb. 11 (2) ; 5 others, not frosted, were on 3rd 

 March placed in the forcing -box, and they emerged 

 March 9 (1), 10 (1), and 11 (3). All the 20 were perfectly 

 healthy specimens. Comparing the first 10 with the 



