Chap. XI. 
BUTTERFLIES AND MOTHS. 
397 
to entomologists the most useful character for detecting 
the affinities of the various species. 
Now if we turn to the enormous group of moths, 
which do not habitually expose to full view the under 
surface of their wings, this side is very rarely, as I hear 
from Mr. Stainton, coloured more brightly than the 
upper side, or even with equal brightness. Some ex- 
ceptions to the rule, either real or apparent, must be 
noticed, as that of Hypopyra, speci lied by Mr. W orrnabl . 12 
Mr. E. Trimen informs me that in Guenee’s great work, 
three moths are figured, in which the under surface is 
much the most 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 
wino-s in certain other Geometrae 13 and quadrifid Nocture 
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 considerable 
“time,” and thus exposing to view the under surface. 
Other species when settled on the ground or herbage 
have the habit of now and then suddenly and slightly 
lifting up their wings. Hence the lower suiface of the 
wings being more brightly-coloured than the upper sur- 
» ‘Proc. Ent. Soc.’ Mai ch 2nd, 1808. 
13 See also an account of the S. American genus Erateina (one of 
the Geometrae) in fc Transact. Ent. Soc. new series, vol. v. pi. xv. and 
xvi. 
