328 



segment, and the greater portion of fifth segment yellow, these mark- 

 ings being connected by means of a narrow yellow marginal line; 

 venter with a conspicuous oblong yellow spot on lateral margins of 

 each segment. Coxae black, legs yellow. Halteres yellow. 



Eyes contiguous; antennae short, barely longer than arista. 

 Thoracic hairs yellow, particularly noticeable on anterior central por- 

 tion; scutellum shorter than the thorns. Legs normal. Fork of third 

 vein at right angles to that vein; the 4 veins leaving discal cell indis- 

 tinct. 



Female. — Differs from the male in the color and structure of the 

 head as follows : frons glossy black, about one third the head-width, 

 almost parallel-sided, in profile distinctly higher than eyes, a more or 

 less distinct suture or depression visible on center, a rather broad yel- 

 low line on each side, extending from a short distance above the 

 antennae to the anterior ocellus, dilated at its lower extremity, where 

 it almost touches the eye-margin, of nearly uniform width through- 

 out the remainder of its length, and separated from the eye-margin 

 by a space equal to its own width, the space between slightly in- 

 creased at the upper extremity ; face as in male but the yellow spots 

 larger; posterior eye-orbits yellow, blackened slightly below and sep- 

 arated from the large yellow vertical spot by a narrow black line. In 

 olher respects as the male. 



Length, 3.5-4 mm. 



Originally described from Carolina. Loew described the same 

 species, under the name uni fascia fa, from Pennsylvania. Melander 

 has recorded unifasciata from Virginia and Illinois. I have seen 

 specimens from Monticello, Illinois (Hart and Malloch) and Lafay- 

 ette, Indiana (J. M. Aldrich), taken in June and July. 



OxYCHRA CROTCHi Osteu Sackcu 



Oxycera crotcM Osten Sacken, Western Diptera, p. 212. (1877) 



Original description : ''O.rycera crotchi n. sp., ? . — Abdom.en with 

 three lateral yellow spots on each side and an apical triangular one, 

 all connected by a narrow yellow margin; femora black, with yellow 

 tip ; tibiae and tarsi yellow. Length 8 mm. 



"Female. — Face and front yellow, with a broad black stripe in the 

 middle ; posterior orbits yellow ; vertex, cheeks under the eyes, and 

 occiput black. Antennae: basal joints black (the rest wanting). 

 Thorax black, opaque ; a yellow stripe from the humerus to the ante- 

 scutellar callus is interrupted a little beyond the middle, a pair of nar- 



