1919] Crampfon — Terga and Wing-Bases of Insects 61 



shown in Fig. 5 this is not the case, due to the fact that it was 

 chosen to ilhistrate the tendency in some Neuroptera for the wing 

 base and tergum to approach the condition occurring in certain 

 Mecoptera and Diptera. In both the Trichoptera (Fig. 2) and 

 the Lepidoptera (Fig. 4) there is a marked tendency for the tegula 

 "t" to become large — a tendency which is somewhat less developed 

 in the Hymenoptera (Fig. 1) and in certain Neuroptera, although 

 there are evidences of it in these insects as well. The tegula, 

 however, is best developed in the Trichoptera and Lepidoptera, 

 and in these insects the region labeled "s" (Figs. 2 and 4) is very 

 similar in outline, as is true of the incision in the margin of the 

 region immediately behind that labeled "s." In both Trichop- 

 tera and Lepidoptera (Figs. 2 and 4) the alar ossicle labeled "n" is 

 comparatively well developed, as is also true of the sclerite labeled 

 "a"; and in both Trichoptera and Lepidoptera, there is a marked 

 tendency toward the formation of a membranous area "ma" 

 (Figs. 2 and 4) in the postscutellar region "psl." 



The above-mentioned similarities between the Trichoptera and 

 Lepidoptera are in full accord with the evidence of close relation- 

 ship drawn from other sources, such as the presence of a coiled 

 proboscis in such Trichoptera as Plectrotarsus gravenJiorsti, the 

 lepidopteroid character of the venation and wing-outlines of cer- 

 tain Trichoptera, the similarity in the antennae, legs, genitalia, 

 outline of the abdomen, and other features which point very 

 clearly to a community of descent, or a merging of the lines of 

 descent of the Lepidoptera and Trichoptera as they are traced 

 back to their point of origin; and (as has been pointed out in a 

 paper soon to be published in the Trans. Ent. Soc. London, dealing 

 with the phylogeny and interrelationships of the higher insects) 

 these anatomical features of the adult insects, as well as the study 

 of larval characters, clearly point to the Trichoptera rather than 

 the Mecoptera as the stem forms from which Lepidoptera have 

 sprung, despite the efforts of Handlirsch and Tillyard to emphasize 

 the mecopteroid character of the venation of the lepidopterous 

 wing. The Mecoptera are also related to the Lepidoptera, but 

 less closely than the Trichoptera are, and I am more inclined to 

 regard the lines of descent of the Mecoptera, Trichoptera, and 

 Lepidoptera as springing off from a common point of a stem re- 

 sembling the Neuroptera very closely, though the lines of descent 



