14 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 



While the urif;iii of the eriiciform larva' of the Ceramuycida-, ( "urciilioiiidie, Scolytida-, and 

 other wood-boring and seed-inhabiting and burrowing Coleopterous larva' in general, is plainly 

 attributable to adaptation to cliaiiged modes of life, as contrasted with the habits of roving, 

 carnivorous, canipodeiforni larva-, it is not so easy to account for the origin of the higher nietabolous 

 orders of Diptera, Lepidoptera, and Ilymenoptera, whose larva* are all more or less eruciform. We 

 are f )rced to adopt the sui>positioa that they have independently originated fi'otn groups either 

 belonging to the Neuroptera. (in the modern sense) or to some allied but extinct group. 



i-{estricting ourselves to the Lepitloptera; as is well known the Lejiidoptera are now by some 

 believed to have descended from the Trichoptera or from forms allied to that group. We should, 

 however, prefer the view that the Lepidoptera, Trichoptera, and Mecoptera had a common origin 

 from some earlier, e.xtinct group. The similarity of the imagines of certain of the lower Tiueina 

 and certain of the smaller Trichojitera is certainly very marked, the most signilicant feature being 

 the fact that the mandibles in the two groups are either absent or minute and rudimentary. 



We have attempteil, however,' to show that the larva' of the l'anorpida\ judging from Urauer's 

 figures and descriptions, are much nearer in shape and ornamentation to caterpillars than to 

 case worms. Hence, it seems to us probable that the ancestral or stem form of the Lepidoptera. 

 was probably a now extinct group, somewhat intermediate between the Mecoptera (Pauorpidie) 

 and the Trichoptera. 



The primitive cateiyiUai-.—Wi' would suggest that the earliest type of Lepidopterous larva 

 was allied to some Tineoid which lived not only on land but on low berbage, not being a ndner or 

 sack bearer, as these are evidently secondary adaptive forms. It is evident, when we take into 

 account the remarkable changes iu form of certain mining Tineoid larvte described and figured by 

 Chambers- and by Dimmock,' that the flattened, footless, or nearly apodous mining larva> of the 

 earlier stages are the result of adaptation to their burrowing habits. The generalized or primitive 

 form of the first caterpillar was, then, like that of Tineoid larvi« in general, and was an external 

 feeder rather than a miner. The body of this forerunner or ancestor of our present caterpillars 

 (which may have lived late in Carboniferous times, just before the appearance of flowering plants 

 and deciduous trees) was most probably cylindrical, long, and slender. Like the Panorpid larv;^, 

 the thoracic and abdominal legs had already becom differentiated, and it (littered from the larviB 

 of Pauorpids in the plantar of the abdominal legs being provided with perhaps two pairs of 

 crochets, thus adapting them for creeping witli security over the surface of leaves and along twigs 

 and branches. The prothoracic or cervical shield was present, as this is api)arently a primitive 

 feature, often reappearing in the Noctuid:e, and sometimes in the liombycina, and always present 

 in the boring larvte of the Ilepialidie and the Cossid;e. 



As tactile hairs, defensive or locomotive set:e, and spines of manifold shapes occur in worms, 

 often arising from fleshy warts or tubercles, it is reasonable to assume that the piliferous warts of 

 lepidopterous larvre arc a direct heirloom of those of the vermian ancestors of the insects. In our 

 primitive caterpillar, then, the piliferous warts were present, eventually becoming arranged as 

 they now are in ordinary Tineoid, Tortricid, Pyralid, Geometrid, and Noctuid larva'. 



Orif/in of the (jreen color of cnterpillnrs.—Tha cuticle may at tirst, as in that of caseworms and 

 Panorpid larva', have been colorless or horn colored. But soon after habitually feeding in the 

 direct sunlight on green leaves, the chlorophyll * thus introduced into the digestive system and 

 into the blood and the hypodermal tissues would cause the cuticle to become green. Afterwards, 

 by further adaptation and by heredity this color would become the hue in general common to 

 caterpillars. Moreover, some of the immediate descendants of our primitive caterjjillars were 

 probably lighter in hue than others; this was probably due to the fact that the lighter-colored ones 

 fed on the pale-green underside of the leaves, this ditterence becoming transmitted by heredity. 



I Third Report U. S. Entomological Commission. Genealogy of the Hexapod.a, pp. 297-299, 1883. Also American 

 Xaturalist, Sept., 1883,932-94,-. 



-American Entomologist, iii, 1880, 2r)5-2(i2; Psy(h<', ii, 81, 1H7-22T; iii, (i3, 135, 117; i'v, 71. KcIVts to the larvio- 

 of the "Gracilavid;e" and " Lithocolletidiu" together with Plivllociiistis. 



= Psyche, iii, Aug., 1880, 99-103. 



*See the important and <iuito conclusive footnote by Professor Meldola on p. 310 of Weisniann'.s Stuilics in the 

 Theory of Descent, Vol. i ( " I have alreiidy given reasons for suspecting that the color of green caterpillars may bo 

 due to the presence of chlorophyll in their tissues, Proc. Zool. Soc., 1873, 159. — R. M."). 



