COMMON COCKROACH. 397 



two oviducts pass ventrally to the terminal nerve structures, to form 

 a common vagina, which opens between the sterna of the eighth and 

 ninth abdominal somites. 

 p. Colleterial glands of the left side. 



The tubules of each side join a single stem, and the two ducts thus formed 

 open by a single orifice into the vagina within the angle bounded by the nerves of 

 the last abdominal ganglion. The two glands (right and left) have, according to 

 Kadyi, an identical structure, and consist of tubes dividing dichotomously. But 

 the left gland is large and hides the right, and its secretion contains crystals of 

 Calcium oxalate. The secretion itself is a yellow granular fluid which hardens on 

 exposure to air and forms the cocoon. This cocoon lodges as a rule sixteen eggs 

 disposed in two rows, an egg on one side alternating with an egg on the other. 

 The spermatheca opens in front of the colleterial duct. It consists of two short 

 tortuous caeca with a short common duct. Spermatozoa are said by von Siebold to 

 be found in both these caeca. The usual structure in Insecta of this apparatus is 

 a bursa copulatrix with muscular walls and chitinous lining and an appended gland. 

 In thus possessing two receptacula seminis instead of one, as also in having eight 

 ovarial tubules instead of twelve, as is usually the case in Orthoptera, the Cockroach 

 presents more or less aberrant arrangements. 



Ovarial tubes. Brandt, M^moires de 1'Acad. Imp. St. Petersburg, (7), xxi. 1874. 

 Id. Das Ei, Leipzig, 1878; Id. Z. A. viii. 1885. Ovum of Nepa and Notonecta, 

 Will, Z. W. Z. xli. 1885 ; of Colymbetes fuscus, Id. ibid, xliii. 1886; Of various 

 Insecta, Korschelt, Z. A. viii. 1885 ; Von Wielowiejski, Z. A. ix. 1886. Micropyle 

 and chorion, Korschelt, Z. A. vii. 1884. 



Development of ovarial tubes in Insecta. Jaworoski, Z. A. v. 1882. Cf. Bal- 

 biani, Recueil Zool. Suisse, ii. 1885 ; Schneider, Zool. Beitrage, i. 1885. 



Genital apertures in Insecta. Palmdn, Ueber paarige Ausfuhrungsgange der 

 Geschlechtsorgane bei Insecten, Helsingfors and Leipzig, 1884; cf. Id. M. J. 

 ix. 1883. 



Development of sex ducts. Nusbaum, Z. A. v. 1882. 



Spermatheca. Von Siebold, Miiller's Archiv (Arch, fur Anat. und Phys.) 1837, 

 p. 393; of P. orientalis, p. 408. Leydig, Nova Acta, xxxiii. 1867. 



Colleterial glands, and egg-capsule. Kadyi, Z. A. ii. 1879. Egg-Capsule. 

 Hallez, A. N. H. (5), xvi. 1885. 



Female genital armature. De Lacaze-Duthiers, A. Sc. N. (3), xvii. 1852. Cf. 

 Huxley, Anatomy of Invertebrata, p. 405, p. 433. Development of these parts 

 in Insecta. Packard, Guide to the study of Insects, 1872, p. 15. In various 

 Hymenoptera, Kraepelin, Z. W. Z. xxvii. 1873 ; Dewitz, ibid. xxv. 1875 ; xxxviii, 

 1877. 



