MEMOIES OF THE NATIONAL ACADEMY OF SCIENCES. 53 



of Lepidoptera, only tbe larviE of the Trichoptera, Panorpid.ie, and Tenthredinida' approacliing 

 tliem. tlicy do not seem to attbrd salient features of value for subordinal charaeters. Yet there 

 are some archaic features, such as the arranjiement of the hooks on the abdominal legs, the 

 presence of eversible coxal glands on the under side or on the sides of the body; and in the larva 

 of Eriocephala we have subordinal characters in the absence of a functional spinneret, also in the 

 extraDidiiiaiily large size of the antenna', and of the maxillary palpi of that genus. 



The process of specialization in the larva has effected not so much the general form of the 

 body as the armature of the abdominal legs and of the body. Chambers, and also Dimmock, 

 (Psyche, iii, 99, 1880) has shown in Lithocolletis and in Gracilaria, especially, the changes which 

 take place in the head and mouth parts as well as feet of the larva after the first, molt, in adapta- 

 tion from a mining to a free existence. Bat in free-feeding forms it is difticnlt to distinguish a 

 normal Tiueid larva from a Tortricid or Pyi'alid larva, and as yet no characters diagnostic of them 

 and other families have been indicated. With the exception of the larvtB of certain Tineina, of 

 the Cochliopodidie (Limacodidic), of the Psychida-, those of the Ilesperians aiul the onisciform 

 caterpillars of Lycaenidie, lepidopterous larvfe are remarkably homogeneous in form, as they are 

 in habits. The only reliable larval characters for distinguishing families are the ditterences in the 

 piliferous tubercles, the number of hairs or set;e arising from a tubercle, or the shape and size of 

 the tubercles themselves, and evei; within the limits of any family there is great variation in 

 these, as seen in the Saturniida', or the Ceratocampida?, or Arctiidir, etc. 



The resemblance between the larva» of the Trichoptera and the Lepidoptera is remarkably 

 close, their internal and external anatomy being nearly the same, the Lepidoptera differing chiefly 

 in the presence of abdominal legs; these, however, being absent in Micropteryx. 



Supposing that the Leitidoptera did spring from some nenropterous group allied to the stem 

 form of the Trichoptera, the type at once after the primitive lepidoptera ceased to live in the watei-, 

 if its ancestors were aquatic, assumed abdominal legs, hooks developed on them, at first a pair, then 

 more until two complete rows appeared, and the larva was fitted to climb the stems of plants in 

 order to feed on the leaves. Eventually we may imagine that the larva", owing to the attacks of 

 insect parasites, sought shelter by mining leaves, seeds, twigs, stems, trunks, and even roots of 

 plants. In adaptation to these novel surroundings, the mining forms by disuse lost their legs, 

 their bodies became flattened and otherwise modified as in certain Tineina, or the sack bearers 

 were modified in adai>tation to tlieir peculiar habits. Tliis great diversity in the mode of obtain- 

 ing their vegetable food and their exposure to varying surroundings resulted in manifold special 

 adaptations in ornamentation and armature, hence the groups most successful in the struggle for 

 existence became very numerous in genera and species. 



The generalized forms may be detected by the larvte having one-haired warts, with minute 

 tubercles without spines, but other primitive forms have large tubercles, warts, humps, or highly 

 colored lines, bands, or spots. While the larval characters are useful in distinguishing genera 

 or families, they do not appear to present salient subordinal characters, as they do in Coleoptera, 

 Diptera, and Hymenoptera. 



(i. The generahzed pupal forms are those nearest to the pupa libera of Trichojitera and the 

 Neuroptera, etc.; such is that of ilicropteryx. Those pui>;e with more or less free abdominal 

 segments, the Fupw incompletw of Chapman, are plainly more archaic or genei'alized than those 

 belonging to his division, Pupw obtecfa; which comprise the modern or specialized forms. Where 

 the ends of the maxillary palpi appear externally under the eyes; where the labial palpi are 

 visible; where what we call the paraclypeal pieces are present, we have survivals of the characters 

 of the pupa libera of Micropteryx. When these features have been by modification lost, we have 

 the uniform obtected pujja of the Neolepidoptera, and these characters are so persistent that they 

 are of high taxonomic value. 



7. The pupa, then, is of the greatest importance in defining the larger groups of the haustellate 

 Lepidoptera, and chiefly for the reason tliat the lepidopterous i)ui)a, with its so-called wing and 

 appendage cases, appears to represent not only what maybe called a suljimaginal condition, but a 

 still earlier, lost, or extinct imaginal type, a type perhaps midway between the ametabolous and 

 metabolous series. This is suggested by the wing-cases which are as in ametabolous nymphs, 

 such as those of Dermaptera, Termitida', and Psocida-, as well as of Hemiptera; and, as shown 

 by Spuler, the venation of the lepidoi)terous i)upa is almost identical with that of the Blattidai 



