MAY FLIES AND MIDGES OF NEW YORK 167 



The first posterior cell and the cell within the fork of the cubitus 

 are much longer than in 0. unimaculatus Lw., and the 

 latter cell is longer and broader. Hence it happens that although 

 in both species the cross-band-like spot is placed immediately 

 inside of the proximal end of the fork it occupies the middle of 

 the wing in C . unimaculatus, and is much nearer the base 

 in C . b i m a c u 1 a t u s . The abdomen of the male ends in a 

 comparatively large and conspicuous forceps (the " hypopygium 

 maris globosum " in Mr Loew's description of C. maculatus 

 seems to indicate a different structure?) . (O. S. loc. cit.) 



Catskill mountains and Quebec (Osten Sacken 1877). Several 

 male specimens from Lake Forest, Illinois, received from Profes- 

 sor Needham. New Jersey (Johnson, 1904). 



2. Chasmatonotus univittatus Coquillett 



1900 Chasmatonotus Coquillett. Proc. Wash. Acad. Sc. 2 : 395 



Male. Black: the bases of antennae, front corners and hind 

 end of thorax, pleura, except the lower portion and one or two 

 spots; halteres, trochanters, and bases of femora and of tibiae, 

 yellow; posterior margins of abdominal segments whitish, meso- 

 notum polished; abdomen subopaque; wings black, the extreme 

 base and a vitta extending from it three quarters the length of the 

 wing, between the medial and cubital veins, white; length 2.5 mm. 

 Sitka, Alaska. 



3. Chasmatonotus unimaculatus Loew' 



1864 Chasmatonotus Loew. Berl. Ent. Zeit. 50 



1878 Chasmatonotus Loew. O. S. Cat'l. Dipt. N. A. p.22 



Male and female. Black, with black wings, having a Avhitish 

 spot on posterior margin. Length 2 mm. ; wing 2 mm. 



Head black, the eyes in both sexes separated by a wide shining 

 front. Proboscis short, black; palpi black, four-jointed; the first 

 joint short, the next two moderate, the second clavate; the third 

 stouter; the fourth linear, a little longer than the preceding. 

 Antennae fuscous black, short, in both sexes alike; the basal joint 

 globose; the five joints of the flagellum short pilose, the first 

 joint cylindrical, the three following short ovate, the last oval. 

 Thorax black, the dorsum shining, the pleura opaque; scutellum 

 the same color. Abdomen black, subopaque, the first segments in 

 the female lurid; hypopygium of the male black, globose. Legs 

 black, the bases of the femora sordidly yellow and the tarsi in 

 immature specimens cinereous. Halteres black. ^Wings black, 

 with a sujbtriangular white spot extending from the posterior 

 margin as far as R^-i.^ of the wing. New Hampshire (O. S.) 



