INTRODUCTION. XXV 



varied in their habits. The majority of the species fly at niijht or 

 at dusk ; but many fly by day, hke Butterflies, while others are 

 easily disturbed during the daytime. They hold their wings in 

 different positions when at rest, but generally flat or expanded, 

 though many Saturniidcc^ Geonteirce, <S:c., rest with their wings 

 raised over the back, almost in the same way as a Butterfly. 



Moths differ very much in size, too. The smallest Butterfly 

 known {^' Zvuc/ia" barhcrcc^ Trimen) is a brown South African 

 species, which sometimes measures less than half an inch 

 across the wings; and the largest Butterflies known (the 

 females of the genus Troides^ Hiibncr) rarely exceed tet. 

 inches in expanse. On the other hand, the smallest Moth 

 known lyNepticuIa niicrotherie/hi, Stainton) measures only about 

 one-seventh of an inch across the wings ; and the largest speci- 

 mens oi Aiiacus ailas, Linnaeus, probably expand not less than 

 a foot (ii^ inches is the expanse of the largest specimen in 

 the British Museum). 



Great attention has been paid lately to the neuration of the 

 wings in Moths, which, although much resembling that of But- 

 terflies in the larger Moths, is frequently more variable and 

 more complicated, while in the smaller Moths it is sometimes 

 reduced to a few radiating lines. Frequently the cell is more 

 or less divided by nervures, or the branches of the sub-costal 

 nervure beyond the upper angle of the cell in the fore-wings are 

 united in such a maniK r as to form a small closed cell. The sub- 

 median nervures on both the fore- and hind-wings are often bifid 

 at the base ; and the costal nervure of the hind-wings is fre- 

 quently absent, or united with the sub-costal for a great part of its 

 length. In many Moths, too, the lowest discoidal ncrvule is 

 united at its base with the upper median, making the median 

 nervure appear four-branched, as in the EqiiitidcB. But il is easy 

 to attach too much importance to a single character; and wc can 

 hardly agree with Prof. Comstock in forming two Families, other- 



