286 DIPTERA FROM SOUTHWESTERN UNITED STATES 



Macrorchis majuscula (Coquillett) 



1904. Coenosia majuscula Coquillett, Invert. Pac, i, 34. 



There is one female of this species in the collection. 



Locality; San Francisco, California, August 7, 1908, (F. E. 

 Blaisdell). 



The only other species of this genus which I have seen from 

 North America is antica Walker (insignis Stein). The latter 

 differs from Coquillett's species in having but one pair of presu- 

 tural dorso-centrals. Both species have two long closely approx- 

 imated bristles at middle of hind tibia, one anterior and one 

 antero-dorsal. There is in the specimen of majuscula before me 

 a weak median postero-dorsal bristle on the hind tibia, which is 

 not mentioned by Coquillett and which does not appear in any 

 of my specimens of antica. 



SCHOENOMYZA Haliday 



There are only three species of this genus listed from North 

 America. One of these, pulicaria V. d. Wulp, I have not seen. 



I have drawn up a key which summarizes the principal differ- 

 entiating characters of the males of the species before me, which 

 should prove useful to students of the group. It is possible that 

 chrysostoma and dorsalis are merely extreme forms of but one 

 species, but there appear to be several forms distinguishable by 

 color, occurring in the west, as shown in this paper. 



Key to Species 

 Males 



1. Frons entirely ochreou.s; each orbit with three bristles 2 



Frons with anterior half conspicuously whitened; each orbit with two 



bristles 3 



2. Cross-veins of wings with conspicuous spot-like infuscation; last section 



of fourth vein only slightly longer than proceding section, and much 

 .shorter than the width of wing at middle aurifrons sp. n. 



Cross-veins of wings faintly or not at all infuscated; last section of fourth 

 vein more than twice as long as preceding section, and at least as long 



' as width of wing at middle convexifrons sp. n. 



3. Upper half or more of face black or blackish brown.. . chrysostoma. Loew 

 Face entirely ochreous 4 



4. Face sulphur yellow, not, or very little, darker than cheeks; upper por- 



tion of second and third antennal joints reddish yellow; when seen 

 from above the ocellar triangle is continued as an opaque black wedge 

 to, or very nearly to, anterior margin of frons. 



dorsalis var. sulfuriceps var. n. 

 Face orange yellow, distinctly darker than cheeks, antennae black 5 



