246 NORTH AMERICAN BLATTIDAE 



CHORISONEURA Brunner 

 1865. Chorisonenra Brunner. Xouv. Syst. Blatt., p. 255. 



Five species were originally included in the genus, one of these 

 since proven a synonym of an older name. In addition to these, 

 a large number of species have been subsequently described. The 

 genus is apparently peculiar to America. 



Genotype: Chorisonenra nigrifrons [Blatta nigrijrons] (Ser- 

 ville), selected by Rehn, in 1903."^ 



Generic Description. — Head triangular, with angles rounded; 

 eyes widely separated; ocellar areas not defined; ocellar spots 

 absent; small but distinct rounded areas, with surface convex, are 

 found meso-ventrad of antennal sockets; face decidedly flattened, 

 weakly convex. Pronotum broad; disk with very weak impres- 

 sions; lateral portions broad and scarcely declivent; lateral mar- 

 gins broadly convex; caudal margin truncate, nearly transverse. 

 Tegmina delicate and narrow, tapering distad to the sharply 

 rounded apex; veins distinct; discoidal sectors oblique. Wings 

 with numerous costal veins, of which part are clavate distad; 

 numerous transverse veinlets between discoidal and median veins; 

 ulnar vein undivided, or with a single distal fork; intercalated 

 triangle large and striking, in many species best termed an appen- 

 dicular field. Sixth dorsal abdominal segment of male specialized 

 mesad. Subgenital plate of male with styles situated mesad and 

 produced in elongate scutes. Subgenital plate of female with a 

 medio-longitudinal, linear cleft distad. Cephalic femora with 

 ventro-cephalic margin supplied with a fringe of hairs, which are 

 shorter and more closely set meso-distad,"^ terminating in a single 

 elongate distal spine;"*' ventro-caudal margin unarmed. Median 

 and caudal femora with ventral margins each supplied with a single 

 elongate distal spine. Tarsi elongate, fourth tarsal joint alone 

 supplied with a pulvillus, which is large, completely filling the brief 

 ventral surface of this joint and roundly produced beyond. Large 

 arolia present. 



'^^ Trans. Am. Ent. Soc, xxix, p. 280. 



3'^ These might well be termed chaetiform spines. 



3'^ A single exotic example of the genus before us is apparently abnormal; in this 

 individual the ventro-cephalic margins of the cephalic femora have each two distal 

 spines. 



