436 THE NORTH AMERICAN EMPIDJE—COQUILLETT. vol. xviii. 



proboscis less than one-third as long as height of head. Thorax, 

 plenra, scntelluiu, and metanotum yellow, scutellum bearing two long- 

 yellow bristles, besides several very short ones. Abdomen blackish 

 brown, the first segment, narrow lateral margins and front margin of 

 each segment, yellow; venter yellow. Legs slender, light yellow, 

 including the cox.e. Halteres light yellow. Wings grayish hyaline, 

 stigma wanting, first vein extending considerably beyond apex of discal 



cell. 



Type. — No. 3238, IT.S.X.M.; length, nearly 4 mm. Two female speci- 

 mens, one of which was captured June 15. 



Localiti/. — New Hampshire and Massachusetts. 



Genus SYNECHES, Walker, 



ANALYTICAL KEY TO THK SPECIES OF SYNECHES. 



1. Wiugs uusiiotted, or marked with only one black spot 2 



Wings marked with a black spot beyond apex of first vein and another at apex 

 of second vein; marginal cell at tip of first A'eiu twice as wide as the 

 submargiual cell at the same point simjihx. 



2. Legs iiartly or wholly yellowish S 



Leo-s wholly black, thorax marked with a white poUinose humeral spot, and 



with a similar one in front of the scutellum; stigma brownish 



nlbonotatuii. 



3. Wings marked with a brown stigmal spot 4 



Wings with a pale grayish stigmal spot, femora wholly yellow. . lujaUnus (p, 437). 

 Wings unspotted, knob of halteres and the entire body black, apex of second 



vein strongly curved, bases of femora black pusilhis. 



4. Maro-inal cell at apex of first vein twice as wdde as the submarginal cell at 



the same point ; knob of halteres whitish 5 



Marginal cell at tip of first vein not wider than the submarginal cell at the 



samepoiut; knobof halteres black debilis (p. 436). 



5. Thorax wholly yellowish rnfiis. 



Thorax marked with three black vitt;e, or wholly blackish thorackus. 



SYNECHES DEBILIS, new species. 



Male. — Antennre black, proboscis and palpi yellow. Thorax yellow^ 

 marked with three vitt* and a lateral spot of yellowish brown. 

 Abdomen and knob of halteres black. Legs yellow, the last tarsal 

 joint, apices of hind femora, middle of hind tibiii? and of their first tarsal 

 joints, black. Wings grayish hyaline, stigma pale smoky brown, mar- 

 ginal cell at tip of first vein not wider than the submarginal cell at 

 the same point. 



Type. — No. 3239, U,S,N.M:, ; length, 3i mm. Four specimens col- 

 lected by the writer in June. 



Locality. — District of Columbia and Maryland. 



