360 Annals Entomological Society of America [Vol. XII, 



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acteristics of the wings, indicates that it is a persistent primitive 

 character handed down from the common ancestor. The 

 NepticuHdas show marked speciaHzation and are the end of a Hne 

 of development, having given rise to no other group. Though 

 they are not apparently to be easily or directly derived from 

 any existing group, the possession of this primitive character 

 undoubtedly allies them more closely to the Micropterygidse 

 than to any other Lepidoptera, and also indicates trichopterous 

 affinities. However, the possession by Micropterygidse and 

 Nepticulidas of this character of primitive Trichoptera, while 

 it indicates relationship to Trichoptera, need not be taken as a 

 basis for regarding them as trichopterous insects, because as 

 shown for Nepticulidce, it has disappeared as a functional 

 structure in males even of the less specialized genera, and its 

 function has been taken over by a single-spined frenulum of a 

 character typical of the males of the more specialized Lepidop- 

 tera. That is, the Nepticulid^ retain evidence of descent 

 in the form of a fibula, but they have progressed far enough in 

 the lepidopterous direction to have developed a distinctly 

 lepidopterous structure. The undoubted relationship between 

 the Nepticulidse and the Micropterygidae indicates that the 

 Micropterygidae are without doubt also lepidopterous, but being 

 a more primitive group, have not traveled thus far toward the 

 usual lepidopterous type in respect to mode of uniting the 

 wings. 



In Rhyacophilidae and other groups of the Trichoptera, in 

 Micropterygidae, Nepticulidae and many of the more primitive 

 Frenatas (Figs. 1, 2, 5, 4a, 8), there is a series of slightly curved 

 stiff spines on the costa of the hind wing near the base, which lie 

 against one of the anal veins of the fore wing, or catch into a 

 similar series on the fore wing, or lie in the fold of the fibula, and 

 aid in holding the wings together. These spines lie beyond the 

 costal sclerite, not on it, as do the true frenulum spines. They 

 are proximal to the humeral vein in forms where this vein 

 is present. This series of spines is without doubt homologous 

 "in the various groups in which it occurs; it may be present in 

 addition to other means of holding the wings together, or it 

 may be the only method of insuring united action of fore and 

 hind wings. It may be functional in females, while in the 

 males of the same species its function has been taken over by 

 some other structure. Thus in Nepticulidas (Braun,' '17), 



