PSILOPUS. 253 



third longitudinal vein ; the hind transverse vein somewhat oblique, 

 not distinctly sinuated. 



Female. It resembles the J* in the coloring of the body and 

 the feet, as also in the neuration and the picture of the wings. Its 

 face has a much denser white dust. The bristles on the second 

 joint of the autenute are considerably shorter, the bristles upon 

 thorax and scutellum are likewise of a lesser length and those 

 before the incisures of the abdomen still much shorter than in the 

 J 1 . The black -bands of the abdomen are not apparent when the 

 latter is not more stretched out than usual ; still the narrow, 

 sharply limited hind margins of the segments appear rather black 

 in a certain light. Feet plain ; pubescence and bristles of the 

 femora and tibia? as in the g , but shorter. Tarsi shorter than in 

 the < ; fore tarsi at least once and a third the length of the tibia?, 

 the first joint about once and a half the length of the four follow- 

 ing, which are of a decreasing length ; upon its outside without 

 bristles. Middle tarsi distinctly longer than the tibia?, their first 

 joint about 1^ the length of the four following taken together; 

 hind tarsi distinctly shorter than the tibia? ; their first joint but 

 little longer than the four following taken together, the length of 

 which diminishes rather rapidly. Peduncle of the halteres brown- 

 ish-black, knob yellow. 



Hab. Chicago, Nebraska, etc. [Common everywhere in the 

 Middle States, 0. S.] 



Observation. Say mentions the occurrence of P. patibidatu* 

 in Mexico. The specimens seen by him may perhaps belong to 

 the following species, which is frequent in Mexico, and he may 

 have been mistaken about their identity with his P. patibulatus. 



5. P. melampus LOEW. and 9. Viridis, saepe ex chalybeo 



viridis, nitidus, facie nuda, alarum fasciis duabus nigricantibus, antice 



conjuuctis et postice abbreviates, pedibus totis nigris. 

 . Abdomine fasciis aequalibus nigris ornato, halteribus ex fusco nigris, 



primo tarsorum anticorum articulo setis nigris armato, articulis sequen- 



tibus duobus non abbreviatis. 

 9 Fasciis nigris abdominis angustis, subobsoletis, halterum capitulo flavo. 



Green, often bluish-green, shining, face without hairs ; the two blackish 

 bands of the wing connected in front and shortened behind ; feet entirely 



black. 

 . Abdomen with black bands of equal breadth ; halteres brownish black ; 



