MEMOIRS OF THE In^ATIONAL ACADEMY OF SCIENCES. 13 



Noli(la\ — Of the .'5 British species, 2 feed on the oak and 1 on the Lawtliorn and sloe. 



Liparidiv. — Of the 12 species, all feed on trees and sbmbs, excejit Lcvlia ca-nosa, which Iiv<^s on 

 leeds and other water plants. It is tufted. 



Xoto(Jonti(hv. — Of 24 species, 1 ( Diloba caruleocephaht. which is smooth, with no protuberances) 

 feeds on the hawthorn and otlier plants. 



Platj/ptericida'. — Of the C species, 5 feed on trees and 1 on a shrub. 



Endromidn: — Tlie single sptcies is arboreal. 



Pnychidtv. — Tlie 2 sjjecies, whose larval habits were known, feed on trees and shrubs. 



Covhliopodida: — The 2 species feed on trees. 



Saturiiiida'. — The single British species feeds on the heather, a shrubby plant. 



Laslocampidw. — Of 11 species, 5 feed on trees, the others ou shrubs and herV)s. 



Nociuo bomhyccs. — All the British sjiecies are reported as "living on trees and shrubs quite 

 •exposed." 



Bomhycoidw. — All the species of Acronycta live on trees and shrubs. 



Influence of a chanije from loic t > high fei-dbuj planU, i. e., from lii-inc/ on an herbaceous to an 

 ■arboreal station. — It appears, then, that the more typical Bombyces, such as the Ceratocampidie, 

 Heniileucidie, Attaci, Notodontians, Cochliojiodida', and Liparida^, are arboreal in their station, 

 their bodies being variously i)rotected by spines, spinulated tubercles, hairs, or tufts. The group is 

 indeed particularly distinguished for the manifold modifications undergone by what are morpho- 

 logically setic, and it is an interesting inquiry whether the great development of these spines and 

 hairs may not have originally resulted from some change in environment, such as that from 

 low feeding to high feeding or arboreal habits. 



It may be objected that the seta^ and spines were originally due to the stimulus arising from 

 the attacks of parasitic insects, such as ichneumons and Tachina^, or that, as hairy caterpillars 

 are not usually devoured by birds, these hairs and spines have originated through natural selec- 

 tion, and are danger signals, indicating to birds that the wearers of such hirsute and bristling 

 armature are inedible. But while the final purpose or ultimate use of such an armature may serve 

 the useful purpose of protection, and while natural selection may have been the leading secondary 

 factor in the iireservatiou of varietal and specific forms of hairy and spiny caterijillars, this does 

 not satisfactorily account for the initial causes of the growth of tubercles, spines, etc. 



If spines and hairs form hedge-like guards against the attacks of parasitic insects, why are 

 they not developed as well in the great nuiltitude of low feeders as in the less numerous high 

 feeders ! It may be said, however, that Euprepia mja is more subject to the attacks of ichneumons 

 than almost any other larv;e. (A. G. Butler in Ann. and Mag. Nat. Hist., 1891.) Everj'one knows 

 how efficacious any hairs or bristles are in deterring ichneumons and Tachmie from ovipositing on 

 caterpillars, and it is well known that naked or slightly piliferous larvie are more subject to their 

 attacks than those which are densely hairy or spinose. 



The eruciform type of lartHV. — In endeavoring to account for the origin of the tubercles and 

 spines, as well as the hairs of caterpillars, let us glance at the probable causes of the origin of the 

 caterpillar form, and of the more primary colors and markings of the skin. 



It was Fritz Miiller who, in his Fiir Darwin (ISCl), maintained that '-the so-called complete 

 metamorphosis of insects, in which these animals quit the eggs as grubs or caterpillars, and 

 afterwards become quiescent pupa^, incapable of feeding, was not inherited from the primitive 

 ancestor of all insects, but acquired at a later period." ' 



In 1869 Dr. F. Brauer' divided the larvae of insects into two groups, the campodea form and 

 raupen form, and in 1871-1873 we adopted these suggestive views, giving the name of eruciform 

 to the larviB of weevils and other coleopterous larviB of cylindrical form, as well as to the larv;e of 

 Diptera, Lepidoptera, and Hymenoptera, all of which are the result of adaptation, being derivatives 

 of the primary campodea type of larva. Brauer's views on these two types of larv;e were also 

 adopted by Sir John Lubbock in his Origin and Metamorphoses of Insects, 1873. 



' Facts and Arguments for Darwin, with additions by the anther. Translated from the German Ijy W. S. Dallas, 

 ■ F. L. S., Loudon, 180'J. 



■'Betrachtiiugeu iiber diu Verwaudluui; der lusekteu iiu Sinue der Drfsceudeuztheorie. VitU. K. K. Zool. bot. 

 Ces. Wien, 1869. 



'Embryology of Chrysopa. American Xaturalist, Sept., 1871. 



