LEPTIFOKM AND ERUCIFORM LARV^. 175 



of insects to those with mouth parts adapted for piercing and 

 sucliing, we must endeavor to learn how fur it was possible for 

 the caterpillar or maggot to become evolved from the Leptus- 

 like lai'VfE of the Neuroptera, Orthoptera, Heniiptera and most 

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

 in relation to two kinds of larv£B most prevalent among insects. 

 "There are two forms of insectean larvjB which are pretty con- 

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

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

 tera, except those of the Phryganeidse and Panorpidje (which 

 are C3'lindrical and resemble caterpillars), are moi'e or less lepti- 

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

 Such are the larvaj of the Orthoptera and Heniiptera, and the 

 Coleoptera (except the Curculionidaj; possibly the Cerambycidae 

 and Buprestidoe, which approach the maggot-like form of the 

 larvas 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 Hymeuoptera, Lepidoptera and 

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

 larvae of the earliest insects were probably leptiform, and the 

 eruciform condition is consequently an acquired one, as sug- 

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

 larvae 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 Hasckel's idea of what were the most prim- 

 itive insects, and noticing how closely they resemble the larvae 

 of Myriopods, says, " specially interesting are those forms 

 among the Poduridae 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 forms (Rau- 

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



*Tlie Embryology of Clirysopa, 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." Faer Darwin, English Trans., p. 121. 



