30 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 



The remarkably woolly and penciled laiv;e of Apatelodes are congrumis with the very distinct 

 imagines of the subfamily ApalcJodlnw, whicli are so well dehiied by their structural characters. 



The hairy and brightly banded larva- of the I'l/yarina; so unlike those of other Notodoiitians, 

 are paralleled by the general ai)pearance and structure of the moths, so much so that the group was 

 regarded as a distinct fiimily (Pyganida') by Duponchel. The larva- of the Euroi)ean Pygii-rinai 

 are hairy aiul gaily striped, and related iu much the same way to our larval Dataua as the imago 

 is to our imaginal Datana. 



The larvae of the subfamily IchilnjnrUuv, represented by only a single genus, need not be 

 coufoundi'd with those of aiiyotlier divisiim of the family, though there is a. great deal of plasticity 

 within the limits of the group. The most generalized species is the larva of /. upicalis (ran) and 

 its allies bnuri (»ii(ltnoma), since it has no large specialized tubercles like those of inclusa and 

 alhosigmn, and the latter species differs, both as regards larva and imago, from /. inclusit. The 

 iin'ongrueuce in this group is not greatly emphasized. 



But in the two next subfamilies there is a striking lack of congruity betweeu the larva and 

 moth, both iu the genera and species. 



Among the Notodoutina- we have Ilyparpax, whose imago is so different, in the shape of the 

 wings and in the color of the body and wings, compared with any other genus of the group or 

 even of the family; yet the larva is very nearly allied to those of Xylinodcs and of Schiziira. 



A remarkable case of incongruence is the larva of Schizura concinna. This well-known 

 caterj)illar, with its formidable armature of long hobnail like spines and its gay head and swollen 

 coral-red dorsal hump, would seem to be the tyiie of a distinct genus, and yet from a study of its 

 adult character it is not separable from the other sj)ec)es of Schizura, and we have dropped the 

 genus (Edcmasia we originally proposed for it from the lack of stable dilferential characters. 

 The freshly hatched larviE, however, is undistinguishable from that of other Schizuriie j^et known, 

 and perhaps we have done violence to the principles of classifi(;ation iu not allowing it to remain 

 in the genus we originally proposed for it. At all events, it with other Schizuric evidently had a 

 common parentage, and it has diverged since it first molt farther away from the stem than others 

 of its cospecies and maybe regarded as an incipient genus. It is also plain that the causes which 

 have acted upon this organism have from the first been of a quite difterent nature from those wliich 

 have been efticient in causing fixed variations in other directions, resulting in the fixation of the 

 other species of the genus. As the change takes place after the first molt, this may have been 

 produced in the Tertiary period. Its larval stages are discussed at some length under the head of 

 the species in the systennitic portion of this work. 



On the other hand, iu the genus Seirodoiita we have a remarkable case of congruence iu its 

 larva as compared with that of Heierocampa manteo. It is almost impossible until after repeated 

 and careful comparisons to distingush the caterpillars of Seiroilonta hiUncata and IT. manteo, though 

 the imagines difl'er somewhat, perhaps generically. At times I have united IScirodanta with 

 Heterocampa, but for the present conclude to keep them apart, as others have done, but really the 

 genus is not so "good" a one as (Edemasia.' 



In the genus Heterocampa, as the name implies, there is a remarkable degree of diversity 

 between the caterpillars of the different species, and our knowledge of them, especially of their 

 early stages, has greatly ext(-nded since the days of Doubleday. 



If we take account of the fully grown caterpillars, it seems (juite evident that there are several, 

 perhaps three, " larval" genera in the group. In H. manteo, (juttiritta, hiundata, obUrpia, and astarfe, 

 the body in the fully grown larva is smooth and unarmed, but in pidrerea, which has a i)air of 

 small tubercles on the prothoracic segment, we have a notable persistance of early larval features. 

 Unfortunately we are not yet familiar with the early stages of this caterpillar. Possibly this 

 species is the stem form of the group. 



In J{. unicolor we have a transfer of the differential generic characters from the prothoracic 

 region to the anal legs. Though the high prothorai-ic tubercle appears in the first stages and 

 perhaps, as in Macrurocampa, in all except the last stage, when the larva is on a level with the fully 



' I have some sljetchi-s made by Mr. Bridgham of a larva in its first three stages which is Schiznra-like, and as 

 it feeds on the elm it is jirobably Seirodouta. Slunild it prove to bo such, tliis genus is a Schizura in the early stages 

 and a Heterocampa in the last. 



