MAY FLIES AM) MII>(;i:S OF MOW YORK 



107 



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

 are nuuli lonjjer than in O. n n i m a c ii 1 a t u s Lw., and the 

 latter cell is lon<»er and broader. Hence it hajjitens that althoujiii 

 in both species the cross band-like sjiol is ]»]aced immediately 

 inside of the proximal end of the fork it ()c(ni)ies the middle of 

 the Aving in C. u n i m a c u 1 a t n s , and is mnch nearer the base 

 in C. b i ma 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 Mv Loew's description of C. m a c u 1 a t u s 

 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 Xeedham. Xew Jersey fJohuKon. 10(14). 



2. Chasmatonotus univittatus Coquillett 

 1900 C h a s 111 a t o n o t u s Coquillett. Proc. Wash. Acad. So. 2 :39o 



Male. Black ; tlie bases of antennae, front corners and hind 

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

 spots ; haltei'es, trochanters, and bases of femora and of tibiae, 

 yellow; posterior margins of abdominal, segments whitish, meso- 

 notum polished; abdomen subopa<]ue; wings black, the extreme 

 base and a vitta extending from it three (piarters the length of the 

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

 Sitka. Alaska. 



3. Chasmatonotus unimaculatus Loew 



1SG4 C li a s 111 a t o n o t u s Loew. Berl. Ent. Zeit. 50 



187S (' h a s 111 a t o n o t u s Loew. O. i^. Cafl. Dipt. X. A. i).22 



Male and female. Black, with black Avings. having a whitish 

 sjiot 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, subojtaque, the first segments in 

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

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

 immature specimens cinereous. Halteres black. Wings black, 

 Avitli a subtriangular white sjiot extending from the ]»osterior 

 margin as far as 11^+- of the wing. N(nv Hampshire (O. S.) 



