214 ANATOMY. 



under surface of which runs a narrow spatel-shaped horny bone, and 

 there is a hair-shaped one at its superior surface ; the aperture (JT) is 

 enclosed by two small horny arches. 



In Melolontlia the penis is only half covered by the prepuce ; its 

 case is posteriorly, particularly upon the upper surface, entirely horny, 

 and distended like a bladder ; two processes originate from it, which 

 are nearly conical, somewhat sloping, and furnished anteriorly with a 

 knob ; these are contiguous beneath, and above they are united by a 

 strons membrane : between them lies the membranous canal of the 



o 



penis, which consists of several folds of the ductus ejaculatorius *. 



In Callichroma moschatum the prepuce is a thin cylindrical bag, 

 which in front is obliquely truncated, and it terminates above with a 

 triangular horny plate. At each of its lateral angles a bone originates, 

 which inclining forwards proceeds beneath to unite itself there with the 

 corresponding one of the other side, forming a perfectly horse-shoe- 

 shaped arch. The case of the penis, which is similarly shaped, lies 

 entirely enclosed within this prepuce; it is likewise more membranous, 

 but terminates in front with two horny valves, the broader and lower one 

 of which entirely embraces the narrower superior one upon the lateral 

 margin, and sends forward two flat processes into the skin of the case. 

 The membranous canal of the penis lies within this case, as a continua- 

 tion of the ductus ejaculatorius (PI. XXVI. f. 1 and 2.). 



Among the Orthopiera we find in Blatta the penis perfectly unsym- 

 metrical. The sexual organs are only visible upon the removal of the 

 dorsal plate, for they lie concealed between the two last ventral plates, 

 and are protected on each side by the short, jointed processes ; we then 

 observe a triangular irregular valve (PI. XXVI. f. 17, 18. o), which 

 covers the passage to the sexual aperture from above, and contiguously, 

 two other, likewise unequal, bags (the same, b and c), which protect the 

 sides, and lastly, beneath, a hook bent upwards obliquely over these 

 parts (the same, d, d). Upon closer examination the superior valve 

 displays itself as a triangular membranous lobe supported by several 

 horny pieces, at the anterior apex of which there is placed a stiff horny 

 hook, which is curved backwards (PI. XXVI. f. 5). The inferior 

 valve, standing opposite to this superior one, is a flat horny plate (f. 

 0. ), with which laterally the right dorsal valve which bends upwards 

 (f. ti. /;) is united by means of a flexible membrane. The yet remain- 



* See Straus, as nhove, PI. III. I. 5., PI. V. f. 13., and PL VI. t. ]. 



