174 NORTH AMERICAN BLATTIDAE 



The Internal structure of this insect has been extensively 

 studied. '^■- 



This is a medium large, blackish brown insect, the males of 

 which have the tegmina falling short of the apex of the abdomen, 

 while in the females these organs are represented by small, ovate- 

 lanceolate, lateral pads. 



Characters of Male. — (Chestnut Hill, Pennsylvania.) Size medium large, form 

 moderately stout. Head much as in Periplaneta americana (ocellar area forming 

 a slightly less obtuse angulation with the interocellar area than in that species), 

 broad; interocular space wide, slightly greater than the interantennal space; sur- 

 face of ocellar area weakly concave, ocelli distinct; maxillary palpi moderately 

 elongate. Pronotum nearly oval, but with greatest width meso-caudal; weakly 

 convex, with disk weakly deplanate latero-caudad. Tegmina covering about two- 

 thirds of abdomen, strongly overlapping. Wings reaching as far as tegminal apices. 

 Supra-anal plate transverse, subrectangulate produced, lateral margins weakly 

 concave to sharp, subrectangulate angle formed with distal margin, which is very 

 weakl>- concave, the plate at this margin becoming subchitinous, particularly 

 mesad. Cerci deplanate dorsad; lateral margins feebly crenate, converging distad 

 to the acute apex. Within the anal chamber sinistrad, a flattened, chitinous shaft 

 extends caudad, narrowing to its least width at base of distal portion; this portion 

 bent dorsad, flattened, broad, tapering to the sharply rounded apex, with a small 

 proximo-sinistral thorn, curving inward. The chamber is nearly filled with chitin- 

 ous plates which converge mesad, from between which a paired, aciculate, chitinous 

 projection is directed sinistrad, and a recurved, slender, chitinous spine is directed 

 caudad. 283 Subgenital plate transverse, convex to distal margin, where it is nar- 

 rowly concave; lateral margins brief, weakly convex produced to the distinct 

 style sockets, distal margin between these broadly convex. ^^^ Styles set in sockets 

 on the free margin at the latero-caudal angles, very slender, cylindrical processes of 

 equal length and thickness, each as long as distance from socket to base of sub- 

 genital plate. Limbs and armament of same as given in generic description. No 

 arolia present. 



282 A full bibliography of such work is given by Bordas in his " Recherches anatomiques 

 histologiques et physiologiques sur les organes appendiculaires de Tappareil reproducteur 

 femelle des Blattes {Periplaneta orientalis L.)." Ann. Sci. Nat., 9 serie, Zool., ix, p. 71 

 to 121, (1909). 



283 The other plates and projections being likewise movable, but more liable to assume 

 different positions when drying, we find that, in dried material, their significant angles 

 and projections are frequently concealed. Examination of living material would be neces- 

 sary to determine their normal position, while, to determine their form in dried material, 

 elaborate and destructive dissections would be imperative. 



In the Blattinae these organs would undoubtedly be found most interesting in struc- 

 ture and of diagnostic value, their general character probably being of decided generic 

 diagnostic value, but, in cases where species can be differentiated without this aid, the 

 genital hook should best alone be considered. 



28' This convexity sometimes shows a feebly angulate condition. 



