56 Journal New York Entomological Society. [Voi xviii. 



above, where they may also join with the black of the vertex, but they never 

 fuse on the lower part of the frons. (2) The cheeks are black. (3) There is 

 a facial black or brown stripe extending from the oral margin to below the 

 antennae. The black of the cheeks and facial stripe is usually well saparated 

 by yellow on the oral margin (Fig. 6), but occasional melanistic specimens 

 show a fusion of these spots. The eyes are bare and in th# majority of the 

 males the facets show an enlarged area above in such a manner that they 

 are marked off from the smaller ones. The line of separation is not constant 

 in extent, but is usually present on the posterior and lower sides of the area. 

 In some cases the line of demarkation fades out as it runs up the anterior 

 border, sometimes on the lower border, and in some specimens it is wanting 

 entirely so that the facets intergrade insensibly in size throughout. 



Thorax metallic blue or bronze, with yellowish pile on the disc, but on 

 the sides with white or grayish-white pile (in one specimen it is somewhat 

 yellowish). Scutellum yellowish with dark reflections, pile yellow intermixed 

 with black on the disc as in arcuatiis. 



Abdomen closely similar to that of arcuatiis, but the yellow lunate spots 

 on segments 3 and 4 show a general tendency to be narrower and straighter, 

 though these differences are appreciable usually only in series. 



Legs as in arcuatus and showing about the same range of variation in the 

 extent of black on the femora. 



Wings with the third vein nearly straight above the first posterior cell 

 (Fig. 8) and showing no tendency to the formation of a loop. Minor differ- 

 ences also exist in the subapical (upper marginal) and postical (lower 

 marginal) crossveins, which are straighter in this species than in arcuatus. 

 These differences are slight but usually perfectly evident (cf. Figs. 7 and 8). 

 Length 9 mm. to 13 mm. 



Geographical range as far as known confined to North America 

 where tl*e species is widely distributed. I have examined in all 35 

 specimens from New Hampshire, Massachusetts, New York, Penn- 

 sylvania, New Jersey, Colorado, California, Washington, Alaska, 

 British Columbia, Alberta and Quebec. 



Without doubt many of the references to " S. arcuatus " in 

 America refer rather to this species or to both, but it is impossible 

 to state with accuracy except in the cases mentioned above. I can 

 be positive in these cases, however, as I have examined specimens 

 of Williston's " var. arcuatus," Banks's specimen from Long Island, 

 and those referred to by Coquillett in his Harriman Alaska Expedi- 

 tion paper. In regard to this species Williston states in a recent 

 letter, " I would call my * var. arcuatus ' var. arcucinctus Walker, 

 supposing that the curvature of the third vein is not specific, and I 

 confess I am troubled about that since I know of no other Syrphid 



