176 NEW YORK STATE MUSEUM 



claws simple. Wings broad, and nearly as long as the abdomen 

 in fresh specimens; usually longer than the abdomen in dried 

 specimens; cinereous in color, the anterior veins conspicuous, 

 brownish or black; media and cubitus pale, posterior margin 

 very delicately ciliate. Halteres usually pale, in an occasional 

 specimen brownish, the knob triangular in outline. Length 3.5 to 

 5mm. (pl.30, fig.13). 



Female. Cinereous black, front and epistome cinereous, eyes 

 but slightly excavated at base of antennae; palpi and antennae 

 fuscous, the latter with 8 joints counting the disk-like basal 

 joint, short-haired (pl.P, fig.7) ; scutellum hemispherical, dark 

 brown, with black setae; abdomen fuscous with short brown 

 hairs, posterior margins to the segments darker except on the 

 extreme edge, which is pale yellow; genitalia small, brown and 

 leaf-like; legs fuscous; claws simple; wings broad, and longer 

 than the abdomen ; anterior veins black; media and cubitus pale: 

 length 3.5 to 5 mm. In other respects like the male. Described 

 from bred and captured specimens. New York, Idaho, Washing- 

 ton State, Greenland. 



Fitch's Chirononius nivoriundus, which I formerly 

 considered a synonym of Diamesa waltlii Meig., I now 

 regard as distinct. 



According to Lundbeck (1898), D. waltlii does not possess 

 cilia on the posterior margin of the wing, he quoting Meigen as 

 authority for this statement; the European specimens, however, 

 which I have do possess these cilia, as do also my American speci- 

 mens. The cilia are quite short and rather difficult to see with a 

 hand lens. D. aberrata Lundbeck (1898, p.290) , according 

 to its author, differs primarily from D. w a 1 1 1 i i in possessing 

 cilia on the posterior margin of the wing ; but since waltlii 

 does have the cilia, this distinction fails, and the two names must 

 be regarded as synonjinous. In the description of aberrata 

 the scutellum and legs are said to be pale brown, while in 

 waltlii, as described above, they are dark brown or fuscous. 

 These differences are at most only varietal in character ; and 

 furthermore, in immature specimens these parts are usually 

 somewhat paler than in mature specimens. 



2. Diamesa chorea Lundbeck 

 1898 Diamesa Lundbeck. Vidensk. Meddel. 291 



Greatly resembling D. aberrata Lundb.; its smaller size, 

 obscure coloring, white balteres and more slender legs will dis- 

 tinguish it. 



