68 RECOKD OP CURRENT RESEARCHES RELATING TO 



tlie sub-galea. Near the end of tlie intermaxilla a piece — distinct 

 from it, as shown in Mantis, Emjjusa, and the mole-crickets — represents 

 the premaxilla, the last organ of the jaw to be accounted for. 



Oviposition of Blatta Orientalis.* — The chitinous structures con- 

 nected with this function are described in a preliminary paper by 

 Dr. H. Kadi, as follows : — 



The genital opening in the female is surrounded by two shovel- 

 shaped processes of the seventh abdominal segment, which fuse in the 

 median line ; their edges are produced into sheet-like membranes, 

 ordinarily folded up, which enclose a space, the " vulva," underlying 

 the last dorsal segment. At the bottom of the vulva is the entrance to 

 the vagina, which projects forwards as a C8ecal tube into the body-cavity ; 

 among numerous other chitinous structures which it contains may be 

 mentioned three pairs of palpoid organs. The vagina also contains 

 several sets of openings. Through the ventral wall enter the two 

 oviducts ; almost opposite, on the dorsal wall, is placed the recepta- 

 culum seminis, behind which occur a right and a left accessory 

 (cement) gland. These glands are asymmetrically developed ; the left 

 is much the largest, and consists of a dichotomously branched efferent 

 duct and of long, opaque, white csecal tubes, which lie on the fat-body 

 and contain crystals of oxalate of lime ; the right is inconspicuous, lies 

 among the tubes of the left, and is devoid of the milk-white colour and of 

 the crystals which characterize the left gland ; their function is that 

 of forming the egg-capsule. When the " cocoon " (egg-capsule) is to 

 be formed, the vulva closes its two external valves together, the cement 

 secretion sj^reads over its inner surface and hardens posteriorly while 

 the ova are being passed into the cavity which it lines. The capsule 

 thus formed, when it contains a certain number of eggs, is partially 

 extruded, becoming brown by the action of the air ; its hinder part 

 bears the imj)ression of the triangular seam formed by the junction of 

 the vulvar valves ; the hinder soft part receives these eggs through its 

 open end, and when full is pushed into the vulva, where it lies until 

 sufficiently hard — the membranous edges of this organ being held by 

 Dufour to constitute an amnion — when it falls out. 



The vulva, if examined, shows at this stage the opening of the 

 vagina with its palps protruding from it. The palps act by grasping 

 and moulding the hinder end of the capsule, whose upper edge or 

 crest is shaped in a ridge formed by the two dorsal edges of the 

 vulvar plates. After an egg has entered the capsule, the latter moves 

 backwards a little, and being again grasped by the vaginal palps, a 

 second of the sixteen tooth-like impressions which it ultimately bears 

 is formed on it by their contact, and in this way the ultimate shape of 

 the capsule is attained. The capsule contains sixteen ova, arranged in 

 alternating rows, owing to their extrusion alternately from one and 

 the other oviduct ; the ova from the duct of one side cross over, and 

 are deposited in the opposite side of the capsule — a conclusion drawn 

 from the positions of the micropyles in eggs in the oviducts and those 

 in the caj)sule respectively : thus the convex side of the egg, carrying 



* 'Zool. Anzeiger,' ii. (1879), p. 632. 



