. Elementary text-book of zoology, tr. and ed. by Adam Sedgwick, with the assistance of F. G. Heathcote. 574 IXSECTA. ovaries are not connected with any special bursa copulatrix, but have three receptacula seminis in connection Avith the vagina (fig. 449), and often end with a retractile ovipositor. There is rarely a striking difference between the two sexes. The males have as a rule larger eyes, which in some cases meet each other in the middle line; their abdomen also is frequently differently shaped to that of the female, and in exceptional cases the colouring is different (B'tbio). The mou
. Elementary text-book of zoology, tr. and ed. by Adam Sedgwick, with the assistance of F. G. Heathcote. 574 IXSECTA. ovaries are not connected with any special bursa copulatrix, but have three receptacula seminis in connection Avith the vagina (fig. 449), and often end with a retractile ovipositor. There is rarely a striking difference between the two sexes. The males have as a rule larger eyes, which in some cases meet each other in the middle line; their abdomen also is frequently differently shaped to that of the female, and in exceptional cases the colouring is different (B'tbio). The mouth-parts, too, may differ ; for example, the male gad-flies (Tdbanidce) are without the knife-shaped mandi- bles, which form the principal part of the female armature. The males of the Culicidce also are without the piercing weapons, and have multiarticulate hairy antenna?, while the antenna? of the female are filiform, and are composed of fewer joints. The metamorphosis is complete, and the larvae, which are usually apodal, have either a clearly separate head with antenna? and ocelli (most Nemo- cera), or a short, usually retracted, cephalic region, without antenna? or eyes (at most with an X-shaped pig- ment spot), with quite rudimentary mouth parts, sometimes with two oral "~T\^f-rlt~*fr~'' hooks, serving for attachment. ^•£*3yjfc2^ In the first case the larva? have SrailfiBi masticating mouth-parts and feed on other animals; in the latter case they are known as maggots and suck up 5fH»> fluids or semi-liquid substances. After pobosca equina (after Packard). several moults the larvas either change within the hardened larval skin to pupae (P. coarctata), or casting the larval skin are transformed into moving pupa? (P. obtecta), which often swim freely in water, and may be provided with tracheal gills. The differences Avhich the development of the Avinged insect from the larval organism presents in the two groups have been already mentioned (p. 550). Many Diptera A
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