Chap. X.I. Butterflies and Moths. 3 1 5 



useful character for detecting the affinities of the various 

 species. Fritz Miiller informs me that three species of Castnia 

 are found near his house in S. Brazil : of two of them the hind- 

 wings are obscure, and are always covered by the front-wings 

 when these butterflies are at rest ; but the third species has 

 black hind-wings, beautifully spotted with red and white, and 

 these are fully expanded and displayed whenever the butterfly 

 rests. Other such cases could be added. 



If we now turn to the enormous group of moths, which, as 

 I hear from Mr. Stainton, do not habitually expose the under 

 surface of their wings to full view, we find this side very rarely 

 coloured with a brightness greater than, or even equal to, that 

 of the upper side. Some exceptions to the rule, either real or 

 apparent, must be noticed, as the case of Hypopyra. 16 Mr. 

 Trimen informs me that in Guenee's great work, three moths 

 are figured, in which the under surface is much the more 

 brilliant. For instance, in the Australian Gastrophora the 

 upper surface of the fore-wing is pale greyish-ochreous, while 

 the lower surface is magnificently ornamented by an ocellus of 

 cobalt-blue, placed in the midst of a black mark, surrounded 

 by orange-yellow, and this by bluish-white. But the habits of 

 these three moths are unknown ; so that no explanation can be 

 given of their unusual style of colouring. Mr. Trimen also 

 informs me that the lower surface of the wings in certain other 

 Geometrse 17 and quadrifid Noctuae are either more variegated 

 or more brightly-coloured than the upper surface ; but some of 

 these species have the habit of " holding their wings quite erect 

 " over their backs, retaining them in this position for a con- 

 " siderable time," and thus exposing the under surface to view. 

 Other species, when settled on the ground or herbage, now and 

 then suddenly and slightly lift up their wings. Hence the lower 

 surface of the wings being brighter than the upper surface 

 in certain moths is not so anomalous as it at first appears. 

 The Saturniidae include some of the most beautiful of all 

 moths, their wings being decorated, as in our British Emperor 

 moth, with fine ocelli; and Mr. T. W. Wood 18 observes that 

 they resemble butterflies in some of tjieir movements; "for 

 " instance, in the gentle waving up and down of the wings as if 

 " for display, which is more characteristic of diurnal than of 

 16 nocturnal Lepidoptera." 



16 See Mr. Wormald on this the Geometric) in 'Transact. Ent. 

 moth : ' Proc. Ent. Soc' March 2nd, Soc' new series, vol. v. pi. xv. and 

 18tto. xvi. 



17 See also an account of the S. 18 ' Proc. Ent. Soc. of London,' 

 American genus Erateina (one of July 6, 18(38, p. xxvh. 



