MAY FI.IKS AND MI1MJKS OF NK\V 



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

 are much longer lh;in in O. unimaculatus Lw., and the 

 latter cell is longer and lroader. Hence il happens that although 

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

 inside of the ]troximal end of I lie fork il occupies the middle of 

 the wing in C. n n i in a c u 1 a t u s , and is much nearer the base 

 in C. b i m a c u 1 a t n 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. in 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. New Jersey (Johnson, 1004). 



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, trochaiiters. and bases of femora and of tibiae, 

 yellow; posterior margins of abdominal segments whitish, meso- 

 notuin 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 



18& Chasmatonotus Loew. Berl. Ent. Zeit. 50 



IMS Chasmatonotus Loew. O. S. Cat' 1. Dipt. N. A. p.'J'J 



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

 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; ihe first 

 joint short, the next Iwo 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 sliorl 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 subtriangular white spot extending from the posterior 

 margin as far as K 4 _._- of the wing. New Hampshire (O. S.) 



