52 ACADEMY OF NATrRAL SCIENCES 



giderable rapidity, constantly advancing its long anterior feet. 

 Its bite is pungent. 



BERIS Latr. Meig. 



B. FTJSCiTABSis. — Thorax piceous-black, polished; tergum 

 reddish-brown, inclining to yellowish on the disk, and with brown 

 incisures. 



Inhabits Pennsylvania. 



Wing hyaline with a pale-brown stigma and nervnreg, origin 

 yellowish-white; thorax with the posterior angles piceous ; feet, 

 anterior and intermediate pairs yellowish-white ; tarsi, excepting 

 the base of the first joint, fuscous, posterior pair reddish-brown, 

 first joint of the tarsi yellowish-white. 



Length one-fifth of an inch. 



The scutel of my specimen is wanting ; I cannot, therefore, 

 ascqrtain its number of spines. 



NEMOLETUS Geoff. Latr. Meig. 



N. PALLIPES. — Greenish-black, thorax tinged with green ; ner- 

 Tures whitish. [30] 



Inhabits Pennsylvania, 



Rostelliform process blued-hlack, polished ; antenna? brown, 

 situate at the base of the rostelliform process ; front with a tri- 

 angular white spot above the antennae; thorax punctured, a tes- 

 taceous line before the wings, and another each side on the basal 

 edge ; poisers and scale pure yellow-white ; costal ncrvures 

 whitish ; feet yellowish, base of the thighs and middle of the pos- 

 terior edges of the segments of 'the venter rufous. 



Length three-twentieths of an inch. % . 



XYLOPHAGUS Meig. 



X. TRIANGULARIS. — Black, sub-glabrous ; thorax plumbeoxis 

 with a black line ; feet testaceous. 



Inhabits Missouri. 



Body black ; head pale plumbeous ; antennse and palpi black ; 

 proboscis pale rufous ; trunk black polished ; thorax, disk pale 

 plumbeous, with a longitudinal polished black line, gradually 

 and slightly dilating behind ; ncrvures fuscous ; haltercs white . 

 feet testaceous, tips of the tarsi and of the posterior thighs and 



[Vol. m. 



