498 Rev. K. St. Aubyn Rogers' Bionomic Notes on 



settled and I saw what it was. Another appeared on the 

 scene soon afterwards.] 



Eitralia (Hj/polimnc.s) wahlhergi, Wallgr. (Plate XXVI, 

 fig. 4), is common, and is, like the Ammtris, a denizen of 

 woods and forests, but its habits are somewhat different. 

 It prefers the more open parts of the woods and generally 

 sits on the upper side of leaves and thence pursues butter- 

 flies of its own and other species ; but it not unfrequently 

 may be seen resting with its wings hanging down in a 

 position entirely similar to that of duminicanus, and such is 

 probably its usual position of rest at night. It is quite 

 possible that this attitude is of great importance in the 

 struggle for existence, and I would offer the suggestion 

 that the period of nocturnal rest may be far more danger- 

 ous to many species than the more active period of the 

 day, when, to judge from the rarity of observed attacks by 

 birds, most butterflies are quite able to take care of them- 

 selves. The period of rest, however, begins for butterflies 

 at a time of the day when birds are most active in the 

 pursuit of food, whereas tlie butterflies are quiescent and 

 would, if discovered, fall an easy prey to their enemies. 

 This principle has also been observed to be in operation in 

 Siam by Mr. N. Annandale,* and in South Africa by Dr. 

 G. B. Longstaff'.t 



Euxanthe %vahcfieldi, Ward, $ (Plate XXVII, fig. 2). 

 The males of this species do not really come into the 

 association at all, but the female is largely modified in the 

 direction of the Amcmris by the increased size of all the 

 pale spots and areas, and also by their colour, which is 

 much lighter and whiter in tint, so that on the wing the 

 butterfly appears to be simply black and white. This 

 resemblance is greatly increased by the shape of the wings 

 as compared with those of its own male, which has the 

 fore- wings exceedingly short and broad, — so much so as to 

 give it a very distinctive appearance, especially in flight. 

 On the other hand, the wings in the female are much pro- 

 duced so as to approximate in shape to those of the primary 

 model. During flight this female bears an even closer 

 resemblance to the Papilionine co-mimic, shown on Plate 

 XXVI, fig. 2, than to the Danaine model (Fig. 1), 

 especially in the prominently spotted dark border of the 

 hind-wing. In habits j&'. ivakejieldi resembles more closely 



* Proc. Roy. Phys. Soc. Edinb., 1900, No. xxix, pp. 439-44. 

 t Tiuns. Eut. Soc. Lontl., 1906, p. 118. 



