SYNOPSIS OF NORTH AMERICAN SYRPHID^. 79 



In comparison of a lai^ge number of specimens from the. East there 

 is little additional worthy of note, except that rarely the tubercle of the 

 face is distinctly brown. From Washington Territory and California 

 I have eight females that do not difter in anything that I can see from 

 the Eastern specimens. The black of the front extends down nearly to> 

 the antennee, the femora are wholly yellow, and the abdominal cross- 

 bands reach quite to the lateral margins of the abdomen, though nar- 

 rowly so as in our Eastern forms. From S. opinator, which is very 

 close, the latter character, and the lower part of the front above the an- 

 tennae not being yellow, are the chief difl'erences. It is very possible 

 that these females may belong with the males described by Baron 

 Osten Sacken as S. protritus, which differ chiefly from the males of 

 S. ribesii in the femora not being black. From Montana and Ari- 

 zona I have examined a number of specimens, both male and female, 

 which undoubtedly belong to «S'. ribesii. A single small male speci- 

 men from iSTorthern California has the cheeks and a broad facial striiie 

 black ; the yellow on the sides is also obscure. It may indicate a dis- 

 tinct species. 



Syrphus torvus. 



Scwva topiaria Zetterstedt (uon Meigen), Dipt. Lapp., 599; id., Dipt. Scand., ii^ 



723; il.id., viii, 3139, 26. 

 Sijrphus topUirius Walker, Liwt, etc., iii, 582; Schiuer, Verb. Zool. Bot. Ges., vii, 



347 ; Faima Austr., i, 304 ; Staeger, Bonsdorf, Malm, etc. 

 S'jrplius torvus Osteu Sacken, Proc. Bost. Soc. N. H., xviii, 139 (1875). 



Hahitat. — Atlantic States, Washington Territory !, Greenland (Stae- 

 ger), Europe, Siberia (auct.). 



(? , 5 . Length, 10 to 12.5™", " Female. Face and cheeks yellow, with a 

 very slight bluish reflection j a faint grayish spot on the cheeks, under 

 the eyes; oral border; in the middle of the notch, usually slightly brown. 

 Front and vertex greenish black ; the former, on both sides along the 

 eyes, with a broad border of yellowish pollen, almost meeting the similar 

 border of the opposite side. Eyes pubescent (in many specimens the 

 pubescence is very much rubbed off and very difficult to perceive). 

 Antennae inserted on brownish-yellow ground ; the dark color of the 

 front begins immediately above their root, forming a blackish-brown 

 arch with a projecting angle in the middle. Antennae dark brown ; third 

 antennal joint more or less reddish below, sometimes altogether dark 

 brown. Thorax greenish, with but little luster; in well-preserved 

 specimens a faint tinge of a geminate, grayish, middle stripe is percep- 

 tible anteriorly ; scutellum dull yellowish, with a slight bluish reflection 

 and black pile. Yellow spots on the second abdominal segment ellipti- 

 cal, prolonged usually as a narrow neck, which reaches forward and 

 touches the margin ; the yellow cross-bands on the third and fourth seg- 

 ments have a very gently biconvex hind margin, with a very shallow, 

 often indistinct, sinus in its middle ; on each side the cross-bands are 

 attenuated and curved forward, so as to reach the anterior margin of 



