230 DIPTERA OF NORTH AMERICA. [PAKT IV, 



II, Four posterior cells. 



25. L,. quadrata 0. S. % and 9 . — Cinerea, abdomiue fuscescente, 

 antenilis palpisque fuscis ; pedibus flavis, femorum, tibiarum, tarso- 

 rumque apicibus fuscis ; alis immaculatis, stigmate pallido, cellulis 

 posterioribus quatuor. 



Yellowish-gray, abdomen brownisb ; antennae and palpi brown ; feet yel- 

 low ; tips of the femora, of the tibiae, and of the tarsi brown ; wings 

 immaculate, stigma pale ; four posterior cells. Long. corp. 0.28 — 0.32. 



Syn. Limnophila quadrata 0. Sacken, Proc. Ac. Nat. Sc. Phil. 1859, p. 241. 



Front and vertex yellowish-gray ; palpi and antenna? brown ; 

 basal joints of the flagellum a little paler; antennte of moderate 

 length ; verticils rather long. Thorax dark yellowish-gray ; with- 

 out distinct stripes ; pleurte slightly hoary ; halteres pale ; feet 

 yellowish ; coxae and basis of the femora pale yellow ; tips of the 

 femora, of the tibiae, and of the tarsi brown. Abdomen brownish ; 

 genitals yellow ; ovipositor slender, long, slightly curved. Wings 

 (Tab. II, fig. 9) faintly tinged with pale brownish ; stigma color- 

 less ; veins brownish. The auxiliary vein ends a little before the 

 inner end of the second submarginal cell ; the subcostal cross-vein 

 is close by its tip ; the praefurca is long, straight, hardly arcuated 

 at its origin ; the petiole of the first submarginal cell is longer 

 than the great cross-vein ; the anterior branch of the second vein 

 is oblique ; the marginal cross-vein is at the inner end of the first 

 submarginal cell, and somewhat -oblique ; the inner ends of the 

 second submarginal, first posterior, and discal cells are nearly in 

 one line ; there are only four posterior cells ; the great cross-vein 

 is about the middle of the discal cell. 



Hab. New York, Virginia, Maryland, etc. May, June. 



The ground color of the head and thorax of this species is a 

 shining black, but it is concealed under a gray dust or bloom, 

 which renders it opaque. 



Although this species has only four posterior cells, while L. 

 recondita, imhecilla, tenuipes, etc. have five, there are abundant 

 signs of a relationship between them. Except the different 

 number of posterior cells, the venation is very much alike : a 

 long, straight praefurca, forming a straight line with the posterior 

 branch of the second vein ; the oblique anterior branch of this 

 vein, with the cross-vein near its origin ; the inner ends of the 

 second submarginal, the first posterior, and discal cells almost in 



