. Elementary text-book of zoology. Zoology. LAKYAL DEVELOPMENT. 549 common the uniform segmentation of the ganglionic chain. Never- theless, it is probable that only a proportionately few of the larval forms have preserved the primitive form, and have a phylo- genetic significance (Ortlioptera), In most cases the insect larva? owe theii1 special peculiarities to secondary adaptations. In exceptional cases, the metamorphosis may be distinguished by quite special larval forms, as for instance in the Pteromalina (Platygaster, Teleas), the eggs of which are laid in other insect larva1 (rig. 458).
. Elementary text-book of zoology. Zoology. LAKYAL DEVELOPMENT. 549 common the uniform segmentation of the ganglionic chain. Never- theless, it is probable that only a proportionately few of the larval forms have preserved the primitive form, and have a phylo- genetic significance (Ortlioptera), In most cases the insect larva? owe theii1 special peculiarities to secondary adaptations. In exceptional cases, the metamorphosis may be distinguished by quite special larval forms, as for instance in the Pteromalina (Platygaster, Teleas), the eggs of which are laid in other insect larva1 (rig. 458). The lowest, usually parasitic larva- are quite vermiform, and are without limbs or a .separate head, the latter being represented by the anterior rings of the body (miajyot* of Diptera and of numerous. FIG. 458.—Larval forms of three species of Plafi/yngfer (after Ganin). a, I, c, Cyclops-like larval stages with claw-like jaws, cephalothoracic shield and abdomen, d, Second larval stage, e. Third larval stage. Hymenoptera, rig. 66, «). In other cases there is indeed a separate cephalic region, but the following thoracic and abdominal segments are entirely without* appendages. The larva? of the Neuroptera, of many beetles, of the TentJiredintflte and butterflies (caterpillars), have, on the contrary, jointed appendages on their three free thoracic seg- ments, and frequently also a greater or less number of rudimentary appendages, the so-called prolegs, on their abdomen. There are two rudimentary antenna? on the heads of these larva?, and a varying number of simple eyes. The mouth parts are, as a rule, adapted for luting, even when the adult animal has a suctorial tube, but, with the exception of the mandibles, they ai-e usually rudimentary. The. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Claus, Carl, 1
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectzoology, bookyear1884
