The above are the principal forms that appear to me Primary (though some doubt may rest upon the ninth and tenth); and probably others will hereafter be discovered, since at present our knowledge of the larvæ of most of the Orders is very limited. And now having given you this generalization of them, as far as they are known to me, I shall next, in a slight survey of those of the different orders, lay before you what I have further to observe upon this subject.
Coleoptera. The Anopluriform coleopterous larvæ, according to Mr. W. MacLeay's view of them, include both those of Coccinella L., Chrysomela L., and Cassida L.; but this appears to me to admit of further consideration. With regard to the two former—those of Coccinella are carnivorous, those of Chrysomela herbivorous; the first is also usually more flat and depressed. As to the latter, Cassida[391], it seems to me to belong to a peculiar type, distinguished not only by its radiated margin, but by the remarkable deflected anal fork on which it carries its excrement. At present I know no analogous form amongst the apterous tribes; I must therefore leave this without a denomination. Perhaps the larva of Hispa or Alurnus, when known, will throw light upon this subject. The larva of Endomychus agrees with that of Coccinella.
There are very few known larvæ that approach to a true Thysanuriform type in this order: that most celebrated is the one supposed to belong to Meloe; but the claim of this to be so considered, is, as we have seen, rather dubious. Should this point at last be satisfactorily ascertained, it will probably carry with it the whole tribe of vesicatory beetles. But even this animal in its general structure is anopluriform: the only circumstance that gives it any analogy to the Thysanura being its anal setæ. Mr. William MacLeay is inclined to regard some of the larvæ of the Malacodermi Latr., but which of them he does not state, as probably belonging to the tribe in question[392]. Those of Lampyris and of Telephorus, as described and figured by De Geer[393], appear to me intermediate between the Anopluriform and Chilopodiform Types: they have no anal setiform or styliform appendages, their mandibulæ are falcate, and their habits seem carnivorous.
Examples of Chilopodiform coleopterous larvæ are more numerous. Of this description are those of Gyrinus, Cicindela, Carabus, and Staphylinus. That of the first, indeed, appears to be the most perfectly Scolopendriform of any yet known; yet the gills or respiratory laminæ, a pair of which issues from each abdominal segment, and two pair from the last[394], prove that there is no slight analogy between it, and indeed many other aquatic larvæ, and the Stomapoda amongst the Crustacea. A remarkable instance of analogy with the Decapoda of the same Class is presented by the larva of Dytiscus, &c. which Mr. MacLeay considers as Chilopodiform, but which exhibits no other resemblance to Scolopendræ than in its predaceous habits and threatening aspect. Its convex, compressed, tapering body, terminating in setæ or laminæ, is certainly much more like that of a shrimp or a prawn; to which the older Entomologists thought it was akin[395], and after which they named it. As Mr. MacLeay's object was, to take all his forms from the Ametabola, perhaps these larvæ will best fall in with his Chilopodiform type; though in the general form of their body they most represent a section (Lepisma L.) of the Thysanura.
Chilognathiform forms are equally numerous in the Coleoptera with the preceding. The wire-worm, or larva of Elater Segetis, as to shape best represents the full-grown Iulus[396], and those of the Petalocera (Scarabæus L., Lucanus L.) the young one.
The most abundant of all forms in this order, is, I think, the Vermiform, upon which I have nothing further to remark.
With regard to Crustaceous forms in Coleoptera, besides the Decapodiform just noticed, I possess two specimens of larvæ of Silphidæ which seem to exhibit a considerable analogy with the Isopodous Crustacea, one rather convex and the other flatter, so as to give the idea of an Armadillo and of an Oniscus.
Strepsiptera. Larva Vermiform.
Dermaptera. Larva Thysanuriform. Type Podura or Sminthurus.