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a curved and often a semi-circular slit-like window. Such 

 curved cracks are exti-emely common in old weather-beaten 

 dead leaves. They are pi-obably produced by drying and 

 shrinkage after much wetting and some decay. 



" On April 23rd last I had the opportunity of testing how far 

 the whole attitude of Polygoaia C-album, dui-ing profound re- 

 pose, is consistent with the interpretation suggested above. By 

 a curious coincidence I had been speaking of the differences 

 between temporary and prolonged resting attitudes in butter- 

 flies, at the meeting of the Entomological Society of France 

 on the evening of April 22nd, and the very next morning saw 

 for the iirst time in my life the position of this species during 

 complete repose. The day was excessively cold for this time 

 of the year, and the butterfly was hanging perfectly torpid 

 from the horizontal rail of a wood fence in a street at Passy. 

 Several excellent but very small photographs were taken with 

 my daughter's camera : enlargements have been made, and 

 from these the actual specimen has been set and photographs 

 of the natural size taken by Mr. Eobinson in the Oxford 

 University Museum. 



'• The specimen which is now exhibited affixed to a piece of 

 stick in precisely the same manner in which it hung from 

 the rail, shows that the two anterior wings are held so far 

 forward that a deep wedge-shaped notch appears between them 

 and the hind-wings. On each side of this notch the well- 

 known ragged outline of the wings is extremely distinct. 

 The two posterior pairs of legs by which the butterfly clings 

 to the supporting surface are light-brown in colour and 

 unexpectedly conspicuous. The antennje are concealed, and 

 the contour of the head does not break that of the costal 

 margin of the anterior wings so as to interfere in any way 

 with the general effect. The whole appearance is consistent 

 with a single interpretation — concealment efl:"ected by resem- 

 blance to a weather-lieaten fragment of dead leaf, deeply 

 notched and ragged, and hanging by two denuded fibro-vaseular 

 ' veins ' standing out far beyond one of the edges. The kind 

 of injury suggested by the ' comma ' only adds another 

 convincing detail to a perfectly hai-monious cryptic effect. 

 " It is interesting to compai'e this mode of concealment with 



