=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. [Illustration: 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_. ] [Illustration: 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. ] At the base of the suranal plate of locusts (Acrydiidæ) is the suranal fork or suranal furcula (_furcula supra-analis_, as we have called it) (Fig. 88, 89, _f_). =The podical plates or paranal lobes.=—In the cockroach and other insects, also in the nymphs of Odonata, the anus is bounded on each side by a more or less triangular plate, the two valves being noticeable in lepidopterous larvæ. They are the _valvulæ_ of Burmeister, and podical plates of Huxley, who also regarded them as the tergites of an eleventh abdominal segment;[38] and the subanal laminæ of Heymons. They are wanting in Ephemeridæ. =The infra-anal lobe.=—Our attention was first called to this lobe or flap, while examining some geometrid larvæ. It is a thick, conical, fleshy lobe, often ending in a hard, chitinous point, and situated directly beneath the vent. Its use is evidently to aid in tossing the pellets of excrement away so as to prevent their contact with the body. The end may be sharp and hard or bear a bristle. Whether this lobe is the modified ventral plate of the ninth urite, we will not undertake at present to say.