. Transactions of the Entomological Society of London. ction. The most characteristically specialised of these in thePlebeiids is the penis, which has to reach the bursa andprovide it with the product of the male glands. The penis consists usually of two portions—the aedeagus,a solid, basal, highly chitinised portion, and the eversiblemembrane (vesica, Pierce); the latter often armed withspines, etc. (cuneus, Stitz, cornuti, Pierce). When pairing takes place the bursa copulatrix is reachedeither by the aedeagus, or by the extension of it constitutingthe eversible membrane. A conclusion one ear
. Transactions of the Entomological Society of London. ction. The most characteristically specialised of these in thePlebeiids is the penis, which has to reach the bursa andprovide it with the product of the male glands. The penis consists usually of two portions—the aedeagus,a solid, basal, highly chitinised portion, and the eversiblemembrane (vesica, Pierce); the latter often armed withspines, etc. (cuneus, Stitz, cornuti, Pierce). When pairing takes place the bursa copulatrix is reachedeither by the aedeagus, or by the extension of it constitutingthe eversible membrane. A conclusion one early arrives at in examining thesestructures is that the aedeagus and the eversible membraneare continuous portions of one structure (or tube), as is, 158 Dr. T. A. Chapman on the of course, obvious when the membrane is everted; butbeyond this, that the external portion of the aedeagusonly differs from the membrane by being chitinised, andthat the length of the external portion of the aedeagusvarying in different species, and often greatly in closely. Fig. 1.—Diagram of aedeagus (founded on Thecla) when retracted. Fig. 2.—Diagram of aedeagus when exserted. Fig. 3.—Similar diagrams of aedeagus in an Erebia. The letteringindicates:— A. Chitinous tube of the aedeagus, external portion. O. The opening in the floor of the genital cavity, throughwhich the aedeagus is advanced and retracted. S. Membranous sheath, sinus (Kusnezov), derived from floorof cavity, that permits this movement, stretched in fig. 1during retraction, gathered together in fig. 2. Z. The zone at which 8 is attached to the aedeagus. B. Internal portion of aedeagus continuous with A, buthaving an outer layer continuous with S. E. Internal opening of aedeagus, where the two layers are reflected into each Ductus ejaculalorius, continuing upwards into A, and reflected from it at its free margin, i. e. continuous with it, forming in this region the eversible membrane (vesica, Pierce) armed with C (cune
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Keywords: ., bookauthorr, bookcentury1800, booksubjectentomology, bookyear1836
