Dr. G. B. Longstaff's Bionomic Notes on BuUerjiies. 655 



ably suggests some such explanation. Perhaps the two 

 explanations may both be true, that heliotropism and list 

 combine the pleasures of insolation with the minimum of 

 risk.* It must, however, be remembered that the listing 

 butterfly exposes to the sun one hind-wing only, and a 

 small portion of one fore-wing. 



§ 11. Tlie inverted attitude of Lycxnids and some other 

 Bviterfiies. 



Supplementing the observations recorded in my paper on 

 " Some Rest Attitudes of Butterflies " f I may add the 

 following notes : — 



North Devon, 1 September, 1907. Walking with Mr. 

 H. Chamjaion along the Woolacombe Sandhills late 

 in the afternoon we observed 39 specimens of 

 Lycxna icarus, Rott., asleep on Marram, Privet, etc. 

 No less than 38 of these were sleeping with the head 

 down, while the exceptional one was horizontal. In 

 many cases the fore-wings were drawn so far back 

 that the costse of the hind-wings overlapped those of 

 the fore-wings. The antennae were porrected and 

 near together. :{: 



Mortehoe, 11 September, 1907. A $ Z. icarus at rest 

 on a Ragwort flower moved its hind-wings alternately. 



* Mr. Marshall calls my attention to the fact that orienting 

 butterflies are always very much on the alert, and do not need 

 cryptic protection. 



t Trans. Ent. See. Lend., 1906, pp. 106-9. 



j In the fourth Eeport of the Rugby School Natural History 

 Society, 1870, p. 17, is an interesting note by Mr. Arthur Sidgwick, 

 which I give at some length as the Report is not easily accessible. 

 " On the 13th August, 1870, I noticed on the road from Bex to 

 Gryon, in the Rhone Valley, a large number of the Chalk-hill Blue 

 (Polyommatus Gurydon), on the umbelliferous plants by the road- 

 side. It was just sunset, and they were all at rest. Their colour 

 and shape effectually protected them from notice. ... I noticed 

 that they all rested head doiomvards. It occurred to me that even 

 this apparently trifling detail of instinct or habit might be pro- 

 tective. The eye in wandering over a plant is arrested more 

 easily than one W(juld suppose by any outline o\it of accord with 

 the general lines on which the plant is constructed." The note 

 is accompanied by sketches showing that the butterfly resting 

 head downwards is less conspicuous than one in the opposite 

 position. 



