352 ACADEMY OF NATURAL SCIENCES 



Body velvet black, with numerous short hairs : thorax with a 

 minute humeral, obsolete piceous spot, and another at base of the 

 wings : scutel with an obsolete piceous spot on each side ; wings 

 large, black, with a violaceous tinge ; the apical furcate nervure, 

 as well as all the other nervures, equally definite. 



Length nearly three-tenths of an inch. 



S. EXiLis. — Halteres nearly half the length of the abdomen. 



Inhabits Indiana. 



Body dusky : antennas as long as the body : stethidium yellow- 

 ish-white : thorax blackish : wings dusky ; apical forked nervure 

 wide, the inferior portion hardly arquated : halters subclavate, 

 about half as long as the abdomen, a little dusky: abdomen a 

 little hairy : feet pale. 



Length % one-thirtieth of an inch. 



PENTHETRIA Meig. 



P. HEROS. — ^Black; costal margin of the wings fuscous. 



Inhabits Mexico. 



Body entirely velvet black : wings dusky ; costal margin fus- 

 cous ; costal edge black ; nervures of the disk-pale. 



Length 9 two-fifths of an inch. 



This I believe to be the largest species, yet discovered, of this 

 small genus. The arrangement of [155] the nervures differ 

 considerably from that of P. holosericea Latr., as represented by 

 Meigen. The male is much smaller and nearly corresponds in 

 the arrangement of its nervures. 



DILOPHUS Meig. 



D. STYGius. — Velvet black, immaculate. 



Inhabits Mexico. 



Body velvet black : thorax with a transverse series of approxi- 

 mate spines on the collar, interrupted in the middle, and a series 

 of smaller ones before the middle of the thorax : wings blackish 

 a little tinged with violaceous : anterior tibia with a series of acute 

 spines on the anterior middle and tip. 



Lensrth one-fourth of an inch. 



[Vol. VI. 



