164 D1PTERA OF NORTH AMERICA. 



Gen. III. PARYDRA STENH. 



Form of the body short and stout. Thorax and scutellum very 

 convex. Front very broad. Antennal bristle on the upper side 

 with a short pubescence, which in some species is difficult to 

 perceive ; bare towards the end. Face very broad, not so much 

 vaulted as in the true Ephydrce, but with a convexity descending 

 more obliquely, on each side with a very characteristic, long, curved, 

 hair-like bristle, beneath which are some shorter hairs, hardly per- 

 ceptible in some species. Clypeus prominent. Cheeks descend- 

 ing beneath the eyes. Lateral borders of the mouth quite bare. 

 Mentum exceedingly thickened. Legs short and rather clumsy. 

 The small transverse vein of the wings is behind the middle of 

 the discoidal cell, consequently proportionately far from the base 

 of the wing ; the posterior transverse vein is not very near the 

 border of the wing, and has a more or less oblique position ; the 

 alula is strikingly large. 



The species of this genus may be divided into two sections, the 

 first of which comprises thickly hairy species with very convex faces. 

 In North America only naked species, belonging to the second 

 section, have been as yet discovered ; they are very similar to the 

 European species of this section ; however, they appear to have 

 more plastic differences than these, and to be consequently more 

 easily distinguished from each other. This can be said at least of 

 the four species known to me, none of which is provided with the 

 email appendage of the second longitudinal vein distinguishing 

 some of the European species. 



Synopsis of the Species.* 



, ( Scutellum with conical warts. 2 



I Scutellum without conical warts. 3 



f Scutellum with two warts. 1 bituberculata, n. sp. 



I Scutellum with four warts. 2 quadrituberculata, n. sp. 



( Face nearly perpendicular. 3 breviceps, n. sp. 



\ Face descending obliquely. 4 paullula, n. sp. 



* The species No. 5 has not been included in this synopsis. 0. S. 



