76 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 68 



suture; the intermediate pair of marginal scutellar bristles are larger 

 than the two other equal pairs: small preapicals usually present. 

 Abdomen black, the last three segments polished on the broad apices, 

 white pollinose at the base, the pollinose bases indented from behind 

 by three to five triangular spots; first and second segments each with 

 a pair of strong median marginal bristles, the last two with uninter- 

 rupted rows of ten to twelve. Wings hyaline; section of fourth vein 

 from bend to hind cross vein equals one-half the preceding section; 

 last section of fifth vein nearl}^ one-half preceding section. Legs 

 black; fore tarsus (pi. 3, fig. 16) with its second joint enlarged and 

 bearing a dense tuft of long bristly hairs on the outside, third and 

 fourth joints strongly flattened, slightly longer than broad, fifth joint 

 elongate and slender; hind tibia on outside with row of about seven 

 uneven bristles extending from base to apex. 



Female. — Front at narrowest 0.43 of head width (measurements of 

 five 0.40, 0.41, 0.42, 0.45, 0.46) ; frontal vitta deeply golden pollinose, 

 two to three times width of parafrontals at lowest orbital; third 

 antenna! joint two and one-half to tliree times the second. Last 

 four joints of the fore tarsus flattened, but not reduced in size, second 

 joint without conspicuous tuft of long hairs. Otherwise, except for 

 usual differences in genitalia, like the male. 



Length, 4.0 to 5.5 mm. 



Type and allotype.— Cat. No. 28158, U.S.N.M., Lewiston, Idaho, 

 male type collected Sept. 25, 1909; no date given for allotype. 



Range. — Idaho, Nevada, California, Washington, British Columbia. 



Host relationships. — Unknown. 



Described from the following: two males and three females from 

 Lewiston, Idaho; two females from Boise, Idaho; one female from 

 Walker Lake, Nevada, July 25, 1911; one male, San Joaquin River, 

 Newman, California. All the preceding collected by Doctor Aldrich, 

 in whose honor the species is named ; these and one male from Pasa- 

 dena, California, are all in the National Museum. One female, Oliver, 

 British Colimibia, 7-vi-1923 (C. B. Garrett), in the Canadian 

 National collection. One female. Lake Paha, Washington, 7-20-'20 

 (R. C. Shannon) in Shjannon's collection. 



PHROSINELLA PILOSIFRONS, new species 



Male. — Front at narrowest 0.36 of the head width (measurements 

 of three 0.34, 0.34 and 0.39) ; front, all of the face and the bucca white 

 pollinose; vitta distinguishable as a gray pollinose band, somewhat 

 wrinkled, moderately divergent posteriorly, at level of lowest orbitals 

 twice as wide as either parafrontal; the- single frontal row inserted 

 at some distance from edge of vitta, and bearing thirteen to fifteen 

 bristles; one or two bristles outside the fiontal row, in the angle of 

 divergence which it fonns near base of antennae; parafrontals 



