FIG. 205.—Terminal parts of the male copulatory apparatus of _Hydrophilus piceus_, torn apart: _vlu_, the two inner lodes; _pn_, penis; _x_, membrane torn from under side of penis; _ej_, ejaculatory duct; _os_, its opening on the under side of the penis, directly under its tip. The muscles, tracheæ, and nerves are not drawn. ]
=Velum penis.=—In the locusts (Acrydiidæ) the penis is concealed by a convex plate, flap, or hood, free anteriorly and attached posteriorly and on the sides to the ridge forming the upper edge of the tenth sternite. When about to unite sexually, the tip of the abdomen is depressed, the hood is drawn backward, uncovering the chitinous penis.
=The suranal plate.=—This is a triangular, often thick, solid plate or area, the remnant of the tergum of the last, usually tenth, segment of the abdomen, the supra-anal or suranal plate, or anal operculum (_lamina supra-analis_) of Haase. In most lepidopterous larvæ this plate is well marked; in those of the Platypteridæ it is remarkably elongated, forming an approach to a flagellum-like terrifying appendage, and in that of _Aglia tau_ it forms a long, prominent, sharp spine. In the cockroach, both Cholodkowsky and Haase maintain that the tenth abdominal segment is suppressed in the female, the tergal portion being fused with the suranal plate (the latter in this case, as we understand it, being the remnant of the eleventh segment of the embryo). As to the nature of the middle jointed caudal appendage in Thysanura and May-flies Heymons has satisfactorily shown that it is a hypertrophied portion of the suranal plate, being in Lepisma but a filamental elongation of the small eleventh abdominal tergite.
FIG. 206.—Copulatory organ of a weevil, _Rhychophorus phœnicis_, seen from above. _A_, _vl_, the lobes united into a capsule; _pp_, torn membrane which connects the capsule with the 9th abdominal segment; _ej_, ejaculatory duct. _B_, the same seen from the side; _mu_, end of the muscle of the penis. _C_, the same as _B_, without the capsule; _os_, opening of the ejaculatory duct (_ej_). Other letters as in _A_. ]
FIG. 207.—_A_, penis (_pn_) of _Carabus hortensis_: _bl_, wrinkled membranous vesicle; _vlu_, the valves; _g_, part of 9th segment. _B_, end of penis of the same, enlarged; _os_, cleft-like opening; also a wrinkled vesicle, as at _bl_.—This and Figs. 203–205 after Kolbe. ]