. The Cambridge natural history. Zoology. S64 HEMIPTERA-HETEROPTERA very protracted passage are not forthcoming. The develop- ment in Nepa has been studied to a certain extent. The apical stigmata are the only pair of the abdominal stigmata that exist in the imago of Mpa, the other six pairs being obliterated; the third, fourth, and fifth, according to Schiodte, in a very peculiar manner: hence, as Martin says,^ the respiratory system is metapneustic. In an earlier stage of the life, however, these six pairs of stigmata exist in functional activity placed in a groove on the under surface of th
. The Cambridge natural history. Zoology. S64 HEMIPTERA-HETEROPTERA very protracted passage are not forthcoming. The develop- ment in Nepa has been studied to a certain extent. The apical stigmata are the only pair of the abdominal stigmata that exist in the imago of Mpa, the other six pairs being obliterated; the third, fourth, and fifth, according to Schiodte, in a very peculiar manner: hence, as Martin says,^ the respiratory system is metapneustic. In an earlier stage of the life, however, these six pairs of stigmata exist in functional activity placed in a groove on the under surface of the body; so that the condition is that termed peripneustic, and remains so till the final moult, when the long siphon appears. In the early life there is a short prolongation from the end of the body in connection with the pair of grooves alluded to, but it is a single unpaired organ, and does little therefore to explain the appear- ance of the siphon, which must, at present, be considered as being suddenly developed at the last moult. The eggs of Nepidae are remarkable objects; that of the common water-scorpion bears seven filaments at one end (Fig. 277); while that of Banatra is more elongate, and bears only two, very elongate, threads. These eggs are deposited in the stems of water-plants, being introduced therein, so that the body of the egg is concealed while the threads project: those of Ilanaira are placed in stems floating on the water, and in consequence of the threads the steras look as if they were infested by some fungus. The struc- FiG. 277. ~ Egg of ture and formation of the egt^s have been ^After Korscheio investigated with considerable detail by Kor- schelt.^ He looks on the filaments as pneu- matic, and considers that they a coating of air to the body ol the egg; they consist of a spongy mass encircled by two layers of egg-shell, both of these latter being peculiar in struc- ture ; the spongy mass is continuous with a layer of the same kind of substance
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1895
