( xlvi ) 



After his return to Denmark the author failed to observe 

 the movement of the hind-wings in Thecla w-album, Knoch., 

 of which the false head was observed by Dr. R. C. L. Perkins 

 in 1888 (" Colours of Animals," Poulton, 1890, p. 208). Prof. 

 Poulton had observed that the movements, which Dr. Chap- 

 man had aptly compared to those of the eccentricities of an 

 engine, only occurred under certain conditions — viz. the short 

 rests, generally on flowers, between flights in hot sun. Dr. 

 Perkins had kindly recalled the circumstances under which 

 his observations were made thirty years ago : — 



" Feb. 16, 1918. 



" It would have been on hot sunny days that I saw the 

 T. w-album moving the wings one over the other in the way 

 described, as I used to go to the place to catch a particular 

 Fossor on the same plant, which was a tall yellow-flowered 

 Umbellifer — the species I forget. It has a strong scent and 

 I have seen as many as half a dozen of the w-album on a 

 single head. The month would be July (after summer term 

 at Oxford). The place was a small quarry cut out in the 

 middle of a thick wood and a very hot place, being an open- 

 ing surrounded by trees, wych-elms, near Badminton, the 

 seat of the Duke of Beaufort, and on his estate. I went past 

 there a year or two ago after a lapse of about twenty-five 

 years and found the wood cut down and I could not detect 

 the quarry. I am sure I often saw the butterflies behave as 

 reported, and occasionally I saw one attacked by wasps 

 (Vespa), which frequented the same flower-heads. I have 

 seen other British Lycaenids make the same movements, and 

 also Lycaenids of most diverse kinds, in Mexico, Australia, 

 etc. It must be a very general habit. 



" The T. w-album used to sit very quietly for a long time 

 together on one head of the flower, if not frightened. I used 

 to find them elsewhere in Gloucestershire and Wilts in abun- 

 dance on the common small-flowered pink thistle and on 

 blackberry, but I cannot now remember whether I saw them 

 move their wings in those places. My memory is most clear 

 as to what I saw in that particular quarry near Badminton." 



Dr. Chapman wrote Feb. 20 and 27 : — 



