Smithsonian miscellaneous collections . e adjectives thysanuriform and campodeiform as appliedto the more simple types of endopterygote larva can have only a de-scriptive value. An endopterygote larva, no matter how thysanuri-form it may be in appearance, is just as truly a winged insect as isan exopterygote nymph, and it is much farther removed than thenymph from its apterygote ancestors. Since it is hardly to be sup-posed that the exopterygote orders and the endopterygote ordersrepresent two primary lines of divergence from primitive wingedinsects, the endopterygotes must have had a long lin
Smithsonian miscellaneous collections . e adjectives thysanuriform and campodeiform as appliedto the more simple types of endopterygote larva can have only a de-scriptive value. An endopterygote larva, no matter how thysanuri-form it may be in appearance, is just as truly a winged insect as isan exopterygote nymph, and it is much farther removed than thenymph from its apterygote ancestors. Since it is hardly to be sup-posed that the exopterygote orders and the endopterygote ordersrepresent two primary lines of divergence from primitive wingedinsects, the endopterygotes must have had a long line of exopterygoteancestry separating them from their apterygote progenitors. Exop-terygote insects were already flourishing in Carboniferous times, en-dopterygotes appear in the Permian; the earliest apterygotes (Col-lembola) are known from the Devonian. Larval abdominal appendages are most fully developed in the larvaof Cory dolus (fig. 9 A). Along each side of the abdomen on the first 56 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 122. Fig. 9.—Abdominal appendicular organs of holometabolous larvae. A, Corydalns cornutus (L.), posterior abdominal segments and , same, terminal appendage of right side, mesal. C, same, cross section of gill-bearing segment. D, Malacosoma americamim (F.), a right abdominal leg cutopen mesally to expose muscles. E, section of leg of a tardigrade, showingmuscles (from Baumann, 1921). F, panorpid larva, under surface of meta-thorax and first abdominal segment. G, same, sternal arc of first abdominalsegment, posterior. H, Dineutes sp., larva, metathorax and anterior abdominalsegments. I, same, inner surface of an abdominal appendage-bearing lobe. J,same, section of left side of an abdominal segment. K, same as I with inner layerof muscles removed. NO. 9 INSECT METAMORPHOSIS—SNODGRASS $J eight segments is a row of lobelike projections between the terga andsterna that fall in line with the bases of the thoracic legs. Each lobebears a long
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Keywords: ., bookcentury1800, bookdecade1860, bookidsmiths, booksubjectscience
