68 BULLETIN 31, UNITED STATES NATIONAL MUSEUM. 



24. — Face yellow ; tlio second and third cross-bands distinctly reach tho lateral margin 



abbreviatus 



Face with a hrown stripe; the second and third bands do not reach the lateral 



margin americanus 



For other species, see descriptions. See, also, Appendix. 



Syrphus arcuatus. 



Scceva arcuata Fallen, Dipt. Suec, 42, 11 (1816); Zetterstcdt, Dipt. Scand., ii, 



719, and vlii, 31.38, 22. 

 Syrjihus arcuatus Meigen, Syst. Beschr., iii,302, 43; Macquarl, Hist. Nat. Dipt., 



i, 53fi, G ; Walker, Ins. Brit., i, 289, 8 ; Schiner, Verh. Z. B. Ges., vii, 344 ; id., 



Fauna Austr., i, 305. 

 Sccn-a lapponica Zetterstedt, Ins. Lapp., 598, 2 (1838). 

 SyrpJms lapponicns ^ch\\iev,Yev. Z. B. Ges., vii, 344 ; Osten Sacken, Proc. Best. 



Soc.N. H., xviii, 149; id., West. Dipt., 326 ; id.. Cat. Dipt., 123. 

 Syrphus agnon Walker, List, etc., iii, 579. 

 Syrphus arcucinctus Walker, List, etc., iii, 580. 

 Syrphus Alcidice Walker, List., etc., iii, p. 579 ; Willistou, Proc. Am. Phil. Soc, 



XX, 312 {Didea). 

 Syrphus arcuatus, var. Mpunctatus Girschner, Wien. Ent. Zeit., iii, 197, pi. iii, 



fig. L 



Habitat. — New England, Wyoming, California, Oregon, Washington 

 Territory, Euroi^e!, Kova Scotia, Hudson's Bay Territory (Walk.). 



(J , 5 . Length, 9 to 12"^™. Face yellow or bluish-yellow ; a median stripe 

 not reaching the antenn.ne, shining black; cheeks more shining green. 

 Antennte dark brown, along the underside more or less reddish. Frontal 

 triangle nearly like the face, but with yellowish dust ; pile black ; a 

 slender black arch above the base of antennae (sometimes dissolved into 

 two spots), bent downward in its middle portion, and immediately below 

 the color is brighter yellow ; front in female black, with black pile, 

 shining, except along the sides, where it is thickly yellowish polliuose, 

 to above the middle, in which place the pollen is narrowly separated. 

 Eyes bare. Thorax deep shining greenish or bluish black, with rather 

 abundant light-colored pile. Scutellum yellowish translucent, with a 

 bluish opalescent reflection, the pile chiefly black. Abdomen black, 

 mostly shining, with three pairs of bright yellow spots, all narrowly 

 separated from the lateral margins ; the first pair a little more broadly 

 separated than the others, straight, transverse, elongate oval ; second 

 and third pairs a little oblique, concave in front, convex behind, the 

 inner ends rounded, the outer ends acute, directed forwards; fourth seg- 

 ment with a narrow yellow hind margin ; fifth with the anterior angles, 

 and the hind border also, yellow. Legs yellowish red ; base of front and 

 middle femora, and tlie hind femora except the tip, black; a ring, or 

 the larger part, of the hind tibiae, and terminal joints (or, except the 

 base) of all the tarsi brownish. Wings nearly hyaline, subcostal cell 

 brownish, stigma darker. 



Variety arcuatus. Third longitudinal vein nearly straight, or only 



