lOO John Henry Comstock 



wings. (Fig. 28). The larvse are leaf miners. This divi- 

 sion is represented by a single family. 



Family Micropterygid^. 



AA. SUBORDER FRENAT^. 



This suborder includes those moths and butterflies in which 

 the two wings of each .side are united by a frenulum, borne at 

 the base of the costal margin of the hind wings, or by a sub- 

 stitute tor a frenulum, a large humeral area of the hind wings 

 (see p. 88) ; and in which radius of the hind wings is reduced 

 to an unbranched condition, while in the more generalized 

 forms the anal area is not reduced. The most available recog- 

 nition character is the dissimilarity in venation of the two 

 pairs of wings, due to the unbranched condition of radius of 

 the hind wings, while this vein in the fore wings separates 

 into several branches. (See Figs. 10-33, except Figs. 27, 28J. 



B. THE MICROFRENAT^. 



Moths of small, often minute, size. The mouth-parts are 

 usually functional. The anal area of the hind wings is not 

 reduced, having three anal veins except in certain minute 

 forms where a broad fringe has been substituted for the mem- 

 brane of this area. 



This division of the order is the Microlepidoptera of authors 

 less the Micropterygidse. But the statement made in man}^ 

 books that the presence of three anal veins in the hind wings 

 distinguishes this group from the Macrolepidoptera is incor- 

 rect, for many of the Macros, possess this characteristic. 



I believe, however, that the retention of the maximum 

 number of anal veins in the hind wings by the Microfrenatse 

 is an index of an essential character of the group ; while in 

 the Macrofrenatse, when it occurs, it is merely an indication of 

 a slight degree of divergence from a primitive type. In other 

 words, I believe that in the Microfrenatse the tendency of 

 natural selection is to develop that mode of flight which re- 

 quires broadly expanded hind wings. While in the Macro- 

 frenatae the tendency has been at first in all groups and con- 



