Resting altitudes in some Lepidoptera. 303 



when the drying attitude is left, the wings are deflexed, 

 but not to a flat position, they are still raised so as to 

 make, between the two sides, an angle of from about 110° 

 to 150°, apparently according to whether gravity, in the 

 position in which the insect happens to be, tends to make 

 them more or less open. This attitude is maintained for 

 something less than an hour; in various instances on 

 touching the wings to ascertain whether they were still 

 soft and this was still a drying position, the disturbance 

 made the insect assume the butterfly attitude; in every 

 case the wings were found to be quite firm. In this species 

 the resting attitude is very different from the usual Geo- 

 metrid one and is identical with the drying position, so 

 that one would suppose that the one might very properly 

 be continued into the other; but a close approximation 

 to the Geometrid attitude is assumed in passing from the 

 one to the other. In a few cases I thought it was omitted, 

 but was never sure that I had not missed it, or that it 

 was shortened or left out owing to some disturbance. 



It may be observed that the intermediate attitude here 

 is very close to the resting attitude of Selenia tetralunaria, 

 but has the wings slightly more deflexed. 



In dealing with the Rhopalocera, I may say that I ob- 

 served carefully and in some numbers only three species, 

 Pieris rapae, Vanessa urticae and Thecla quercus; this is 

 no doubt a rather narrow basis, but for facility of 

 description I assume that they are fairly representative. 



It seemed desirable, opportunity offering, to consider 

 the butterflies. In these the resting attitude is identical 

 with that for drying the wings, viz. the erect dorsal one. 

 I do not know that there is any exception to this rule, if 

 we except the Hesperidae, some of which rest with the 

 wings deflexed, and the Erycinidae, at least the South 

 American species or most of them. These are not, how- 

 ever, in the ancestry of our palaearctic butterflies; some 

 Papilios are also known to rest with deflexed wings. The 

 butterflies who adopt the "butterfly attitude" have 

 cryptic undersides ; those, like the Erycinids, that do not, 

 have undersides not very different from the upper. The 

 whole butterfly ancestry of the species I observed may be 

 assumed to have used the " butterfly attitude " of rest.* 



Therefore, unlike the Geometers referred to, which had 



* I am indebted to Commander Walker and Mr. Kaye for re- 

 minding me of the Erycinid attitude. 



