Dr. T. A. Chapman on attitudes in Lepidoptera. 339 



The detailed notes taken minute by minute during the 

 observations, as I gave them in my first notes on this 

 subject, seem of little value, except as proof that the 

 observations actually were made, so I do not append them, 

 but rather describe the general succession of events in each 

 species, instead of leaving them to be worried out of memo- 

 randa made hurriedly during the observations, and not 

 perhaps easily understood, owing to their abbreviated 

 nature, except by myself. 



The species observed were — • 



P. hrassicae. The wings expand to a position the same 

 as the normal resting position, that in which most Lepi- 

 doptera dry their wings. Almost as soon as one can say 

 expansion is completed, the wings are opened apart to a 

 position in which the fore and hind wings being together, 

 the mid-costae are 8 to 12 mm. apart, and the apices 3 to 

 8 mm., so that the attitude corresponds to that which in 

 P. rapae I have described as bell-shaped ; but the separa- 

 tion is so slight in comparison that this attitude would not 

 in hrassicae suggest any resemblance to the outline of a 

 bell. It is, however, essentially the same, in that the wings 

 being limp the apices approach each other, more than 

 the mid-costae, and are in fact 3 to 8 mm. apart instead 

 of 12 to 20. as they would be if the wings were stiil". They 

 maintain this attitude for about thirty-five seconds and then 

 close, so that the costae are in contact to within 4 mm. 

 of the thorax. They remain so for about forty-five seconds 

 and are again opened to the open position. This alterna- 

 tion is repeated about fourteen or fifteen times. The 

 actual opening and closing takes about ten seconds. 

 The period during which the wings are open is very similar 

 to that during which they are closed, viz. about thirty- 

 five to forty-five seconds. These vary a little in the same 

 specimen and between different specimens, but only by a 

 few seconds. I ought to have said that when open there 

 is the variation of 8 to 12 mm. at mid-costa in different 

 specimens, not in the same specimen, and that 8 mm. at 

 mid-costa corresponds to 3 at apices, 12 mm. to 8 at 

 apices. At the fifth or sixth opening the hind-wing tends 

 to open a little before the fore-wing, separating from them 

 by a millimetre or two in the process. About the seventh 

 or eighth opening, the wings are seen to be stifier than at 

 first, and the apices are as wide apart as the mid-costae. 

 About the tenth the apices open wider then the mid-costae, 



