LEPTIFORM AND ERUCIFORM LARV.E. 175 



of insects to those with mouth parts adapted for .piercing and 

 sucking, we must endeavor to learn how far it was possible for 

 the caterpillar or maggot to become evolved from the Leptus- 

 like larvae of the Neuroptera, Orthoptera, Hemiptera and most 

 Coleoptera. I may quote from a previous article* a few words 

 in relation to two kinds of larvae most prevalent among insects. 

 " There are two forms of insectean larva? which are pretty con- 

 stant. One we call leptiform, from its general resemblance to 

 the larva? of the mites (Leptus). The larvae of all the Neurop- 

 tera, except those of the Phryganeida? and Panorpida? (which 

 are cylindrical and resemble caterpillars), are more or less lepti- 

 form, i. e., have a flattened or oval body, with large thoracic legs. 

 Such are the larva? of the Orthoptera and Hemiptera, and the 

 Coleoptera (except the Curculionida? ; possibly the Cerambyciclse 

 and Buprestida?, which approach the maggot-like form of the 

 larvae of weevils). On the other hand, taking the caterpillar or 

 bee larva, with their cylindrical, fleshy bodies, in most respects 

 typical of larval forms of the Hymenoptera, Lepidoptera and 

 Diptera, as the type of the cruciform larva, etc. * * * The 

 larva? of the earliest insects were probably leptiform, and the 

 cruciform condition is consequently an acquired one, as sug- 

 gested by Fritz Miiller."t It seems that these two sorts of 

 larva? had also been distinguished by Dr. Brauer in the article 

 already referred to, with which, however, the writer was unac- 

 quainted at the time of writing the above quoted article. The 

 similar views presented may seem to indicate that they are 

 founded in nature. Dr. Brauer, after remarking that the Podu- 

 rids seemed to fulfil Haeckel's. idea of what were the most prim- 

 itive insects, and noticing how closely they resemble the larva? 

 of Myriopods, says, " specially interesting are those forms 

 among the Podurida? which are described as Campodea and 

 Japyx, since the larvae of a great number of insects may be 

 traced back to them"; but he adds, and with this view we are 

 unable to agree, "while others, the caterpillar-like fqrms (Rau- 

 penform), resulted from them by a retrograde process, and also 



*The Embryology of Chrysopa, and Its bearings on the Classification of the 

 Neuroptera, "American Naturalist," vol. v. Sept., 1871. 



t " It is my opinion that the 'incomplete metamorphosis' of the Orthoptera is 

 the primitive one, inherited from the original parents of all insects, and the 'com- 

 plete metamorphosis' of the Coleoptera, Diptera, etc., a subsequently acquired 

 one." Fuer Darwin, English Trans., p. 121. 



