350 THE ANATOMY OF INVERTEBRATED ANIMALS. 



gin. Articulated beneath its lateral edge are two multiartic- 

 ulate cerci (x), similar to those of the female. 



Beneath the tenth tergum, and hidden by it, are the two 

 podical plates (11) between which the anus opens. The first 

 sternum is small, and may easily escape notice. The second 

 to the sixth sterna are of nearly equal width and length. The 

 seventh and eighth are narrower; the ninth still narrower and 

 longer, about half of its length being covered by the eighth. 

 The covered half is different in texture from the uncovered, 

 being thinner and more transparent, and its anterior margin 

 is deeply notched. The uncovered half is strong, horny, and 

 dark-colored, convex below and concave above ; its free pos- 

 terior margin is obscurely trilobed by two lateral, shallow 

 notches. On each side, a slender, unjointed, setose style, 

 which projects backward and outward, is attached to this 

 sternum. 



Thus, the tergal surface of the abdomen of the male essen- 

 tially resembles that of the female, w4iile the sternal surface 

 differs in exhibiting two sterna more (namely, the eighth and 

 ninth) without dissection. Hence, w^iile in the female the 

 opening of the recto-genital chamber lies betw^een the tenth 

 tergum and the seventh sternum, in the male it lies between 

 the tenth tergum and the ninth sternum. 



When the tenth tergum and the podical plates are removed, 

 a very singular apparatus, the male genital armature, comes 

 into view. It consists of a number of chitinous processes 

 having the form of plates and hooks, the exact form and dis- 

 position of which could be made intelligible only by numerous 

 figures. It may be stated generally, however, that these plates 

 and hooks terminate processes of the sternal region of the 

 tenth somite, on each side of the aperture of the vas deferens, 

 and therefore, though they are of the same nature as the gona- 

 pophyses of the female, they are not their exact homologues. 



The most conspicuous division of the right gonapophysis 

 is a broad plate divided at the extremity into two portions, 

 the inner of which curves inward and ends in two or three 

 sharp spines, w^hile the outer is coiled upon itself so as to 

 resemble a short corkscrew. The left gonapophysis is pro- 

 vided with a long process like a tenaculum, the incurved 

 extremity of whicb is denticulated. 



The alimentary canal of the Cockroach commences by the 

 oral cavity, situated between the labrum in front, the mandi- 

 bles and maxillas at the sides, and the labium, with the large 



