Osten Sacken.J 150 [October 6, 



riorly so as to occupy nearly the whole anterior margin of the 

 segment; in the female this triangle is narrow, and occupies but a 

 small portion of the anterior margin ; thus in the female the yellow 

 of the crossband coalesces with that upon the first segment; the fol- 

 lowing crossbands are entire, the second and third nearly of the 

 same breadth, and not attenuated on the sides; the fourth band, in 

 the male, occupies nearly the whole segment, except a black semi- 

 circle posteriorly; in the female it occupies the anterior half of the 

 segment, and is gently arched and distinctly notched posteriorly. 

 Face yellowish, with a bluish reflection, sometimes brownish in the 

 middle; above the. antennae a conspicuous black spot is surrounded 

 by the yellowish pollen, which covers the rest of the front; antennae 

 reddish, upper half of the third joint, as well as of the preceding 

 ones, brown. Eyes bare. Thorax metallic green ; scutellum yellow- 

 ish, with a metallic green reflection; humeri, and a part of the 

 pleurae, clothed with yellowish pollen. Legs yellow; outer half of 

 the hind femora (sometimes nearly the whole hind femora, except the 

 base), hind tibiae and tarsi, brown; knees yellowish. Wings with a 

 brownish shade on the apex, usually distinct in the female, often 

 nearly obsolete in the male. 



Hub. White Mountains (foot of Mt. Washington, end of June) ; 

 Catskill Mountain House, in July ; North Conway, N. H., in August; 

 Lake Superior (A. Agassiz). Ten male and thirty female speci- 

 mens. Two male specimens have the four anterior femora distinctly 

 infuscated at the base. 1 entertain no doubt that this is the S. 

 dwersipes Macq., only in his description " pieds posterieurs noirs, a 

 hanches noires" must read, " a hanches jaunes." 



S. cinctellus Zetterstedt, is very like this species, and probably 

 identical with it. His description agrees with the North American 

 specimens. A European specimen in the Museum of Comparative 

 Zoology, named by Dr. Loew, does not show any difference worth 

 noticing. 



10. Syrphus geniculatus. 



Syrphus geniculatus Macquart, Dipt. Exot., it, 2, p. 101, 24. 



" Thorace obscure aeneo, nitido; scutello flavido. Abdomine lin- 

 eari nigro, fasciis tribns flavis, interruptis. Antennis pedibusque 

 nigris; geniculis anticis flavis. 



"Long. 31 lines; male. (7.5 mm.) 



Transla'ion. "Face and front black, with blue and green reflections 

 and gray pollen; face with a glabrous, very salient prominence. 



