SYNOPSIS OF NORTH AMERICAN SYRPHID.E. 83 



Femora yellow; the four anterior oues in some specimens brownisli at 

 the extreme base only ; the hind pair with a more or less distinct brown 

 ring on the distal half; four anterior tibiaj and tarsi yellow; the hind 

 tibiae sometimes with a brownish ring, the hind tarsi brownish. 



Male. Front yellow, with a more or less distinct brown spot above 

 each antenna; cross-bands on the abdomen broader than in the female, 

 and distinctly broader than the black interval between them ; posteriorly, 

 they are often nearly straight, sometimes distinctly arcuate, especially 

 the third band. The yellow spots on the second segment are not coa- 

 lesceut, but separated by a narrow black interval (in some specimens sub- 

 coalescent) ; the fifth segment is yellow, with a black spot in the middle. 

 The four anterior femora are black at the base; the hind femora are 

 usually black, with a yellow tip; sometimes there is a trace of yellow at 

 the base; hind tibiae usually with a brown ring in the middle. 



Hah itot.— British Possessions, iSTew England, New York, Delaware, 

 Virginia. In Detroit, Mich., in August, I lound this to be the most 

 common species. It seems also to be common in Texas. Sixteen males 

 and eight females. 



S. aniericanus, $ , differs from S. ahhreviatus, 2 , besides being larger, 

 in the presence of a brown stripe in the face, and of brown spots above 

 the antennae; in the spots of the second segment being altogether coa- 

 lesceut (instead of narrowly interrupted) ; in the cross-bauds not touch- 

 ing (or hardly touching) the abdominal margin, while in 8. ahhreviatus 

 the contact is broad and distinct ; in the cross-bands being (in most 

 specimens) more straight, less sinuate posteriorly. 



8. americanus, $ , differs from 8. ahhreviatus, $ , besides being larger, 

 by the brown stripe on the face, the more straight second cross-baud 

 (less sinuate posteriorly) and by the coloring of the hind femora. In 

 those specimens of 8. americanus which have the hind femora altogether 

 blackish, the yellow space at the tip is narrower than the yellow space 

 in ordinary specimens of 8. ahhreviatus, $ . The yellow spots on the sec- 

 ond segment (in all my <? specimens) do not touch the lateral margin; 

 the black interval, although small, is distinct; in all my <? ahhreviatus 

 these spots distinctly come in contact with the lateral margin. The 

 oral margin is not infuscated here (except, of course, at the point of con- 

 tact with the facial brown stripe). Attention should also be paid, in 

 both sexes, to the difference in the extent of the black coloring of the 

 cheeks, as described above." — Osten Sacken, 1. c. 



A number of specimens from New England and four (5,2) from Mon- 

 tana agree throughout with the preceding description. The front above 

 is rather narrower than usual. 



Syrphus opinator. 



Si/rphus opinator Oaten Sacken, Western Diptera, 327, 1877. 



Habitat. — Washington Territory, California, Oregon ! 



"5, $. Lnugih, 9 to 11'"'". Male. Eyes glabrous ; face, including the 

 cheeks, altogether yellow or reddish yellow; no brown stripe on the 



