438 BULLETIN 63, UNITED STATES NATIONAL MUSEUM. 



Measurementst. — Males: Length, 18.5-19 mm.; width, 6.5-7 mm. 

 Females : Length, 16-17 mm. ; width, 6.5-7 mm. 



Genital characters, male. — Edeagophore of the usual oblong-ovate 

 form. 



Basale variable, oblong, more or less feebly convex, with sides very 

 slightly arcuate. 



Apicale triangular, sides nearly straight, slightly swollen toward 

 base; apex more or less acute; base with middle lobe rather small 

 and rounded, sinuate laterally; dorsal median groove moderately 

 wide apically and linear toward base, 



Clavw stouter than usual, shorter and not so attenuate toward apex. 



Sternite (Plate 2, fig, 11) with each lobe rather long, narrowing 

 somewhat toward apex, the latter rounded; external border evenly 

 arcuate, sometimes slightly angulate at middle, thence oblique and 

 straight from angle to apex; internal border arcuate. Strongly 

 chitinized, surface feebly convex and thickly set with long stiff setae 

 in apical half. Set* do not extend across membrane at bottom of 

 the sinus. 



Feinale (Plate 2, figs. 12 and 13) genital segment triangular, not 

 setose. 



Valviila. — Dorsal plate nearly horizontal, feebly concave or convex, 

 impunctate; external border nearly straight and directly continuous 

 with that of the apex, becoming slightly more prominent at the 

 transitional point on account of the external margin of apex becom- 

 ing slightly sinuate ; internal margin slightly reflexed, feebly arcuate 

 and directly continuous with the internal apical margin which is 

 strongly arcuate on account of the excurvature; apical margin not 

 in the least defined from apex, the dorsal surface of both being di- 

 rectly continuous, the transitional area forming a concave surface. 



Apex produced, not strongly chitinized at- base externally, ex- 

 curved, dorsal surface more or less convex from side to side and 

 directed upward and slightly outward ; ventral surface concave, 

 directed downward and inward ; internal surface more or less mem- 

 branous and set with very short chitinous seta^; tip narrowly rounded ; 

 fossa obsolete with surface not in the least excavated at its usual site. 



Appendage minute and punctiform, without setae and located on 

 the external margin, projecting but slightly beyond the margins of 

 its minute cavity. 



Svj)erior pudendal memhrane attaining the middle of the dorsal 

 plate. 



Ventroldternl .KU7'f(tces not inflated, not strongly convex and gradu- 

 ally tapering from base to apex; submai'ginal groove scarcely visible. 

 Internal margins of the valves contiguous. 



