1914.] NATURAL SCIENCES OF PHILADELPHIA. GUI 



1. Cell3/i absent 2. 



Cell Ml present 3. 



.2. Halteres with the knob darkened; antennae of the male much 



longer than the thorax (eastern United States) eucera 0. S.^^ 



Halteres pale; antennae of the male short (eastern United States), 



rivularis 0. S.^^ 



3. Cell 1st AI2 present; body-coloration yellowish (eastern United 



States) pallida sp. n. 



Cell 1st Mo absent; body-coloration grayish 4. 



4. Size large (length of female 9 mm.) (western United States), 



argentea Doane ^^ 

 Size small (length of the female 6 mm.) (eastern United States), 



novehoracensis sp. n. 



Genus EHAPHIDOLABIS Osten Sacken. 



1869. Rhaphidolabis Osten Sacken; Mon. Dipt. N. Am., vol. 4, p. 284. 

 Rhaphidolabis polymeroides sp. n. 



Antennae elongated, much longer than the head and thorax to- 

 gether, the segments of the flagellum with abundant outstretched 

 hairs; wings with a brown suffusion. 



Male, length about 6-6.5 mm.; wing, 7.4 mm. 



Rostrum brown, palpi dark brownish black. Antennae elongated, 

 if bent backward they would extend to the middle of the abdomen; 

 flagellar segments very long, cylindrical, with abundant outstretched 

 hairs. Head gray. 



Thoracic dorsum brown with three dark brown stripes, the median 

 one longest and broadest, the lateral stripes short, narrowed in 

 front, broader behind; scutum with the lobes dark brown these being 

 continuations of the lateral praescutal stripes; scutellum and post- 

 notum brown with a sparse gray bloom. Pleurae brownish 

 gray. Halteres long, pale at the extreme base, knob dark brown. 

 Legs, coxae brown, more yellowish at the tips, trochanters yellow, 

 femora yellow darkening into brown beyond the base, tibiae and 

 tarsi brown. Wings with a dark brown suffusion, stigma indistinct, 

 veins dark brown with conspicuous hairs; venation (PI. XXVH, 

 fig. 30). 



Abdominal tergites dark brown, the hypopygium lighter brown; 

 sternites more yellowish. 



Holotype, c^, Eureka, Cal., May 22, 1903 (H. S. Barber). 



This insect is conspicuously different from any of the described 



^^ eucera Osten Sacken; Mon. Dipt. N. Am., vol. 4, pp. 281, 282; 1869. 

 "rivularis Osten Sacken; Proc. Acad. Nat. Sci. Phila., p. 249, pi. 2, fig. 16; 1859. 

 ^^argentea Doane; Joiirn. N. Y. But. Soc, vol. 8, p. 196, pi. 8, fig. 19; 1900. 



