Banks, Greene, McAtee, and Shannon — Dist. of Col. Diptera. 199 



Xylota. In fact Myiolepta hella seems to be a connecting link between 

 these two genera ; in this species the hind femora below at the apex are 

 produced into a saw-tooth process, which is as fully developed in the male 

 as in some species of Tropidia ; the frons is bare as in Tropidia. How- 

 ever, there can be no doubt as to the generic affinity of if. bella because 

 of the position of the discal cross-vein and the tubercle on the face of the 

 male. On the other hand Myiolepta seems to be more naturally placed 

 near Brachyopa, as the position of the discal cross-vein would indicate, 

 and some species of Brachyopa in common with Myiolepta have all the 

 femora distinctly swollen and serrated beneath. 



Genus Syrphus. 

 Verrall * in his treatment of the British species of Syrphus points out 

 that three species — ribesii, vitripennis, and torvus — form a group by them- 

 selves, being the only ones " which have the disc of the thoracal squamae 

 hairy." Besides ribesii and torvus, there are the following species in 

 this country possessing this curious character: rectus O. S. (hitherto con- 

 fused with ribesii), knabi n. sp. , opinatorO. S., and possibly also protritus 



0. S. (cf. OstenSacken, West. Dipt., p. 327, 1877), of which the writer 

 has seen no specimens. 



Syrphus grossulariae and xanthostomus have been confused with the 

 above species, all of which have bicolored antennae ; grossulariae can be 

 recognized by the entirely black antennae and the black fringes of hairs 

 on the middle and hind coxae, while xanthostomus has the antennae 

 entirely yellow, the pile on the scutellum yellow and all the coxae, 

 trochanters and legs yellow. 



Specimens of grossulariae in the National Collection are from localities 

 extending from Maine to Pennsylvania, and Metcalf t records this species 

 from Ohio, but we have also one specimen from Kaslo, B. C, and one 

 from Laggan, Alberta. Grossulariae is therefore apparently a northerly 

 ranging species. Of S. xanthostomus, which appears to be rare, the 

 National Collection has besides the type and allotype from Pennsylvania, 

 a specimen from Plummera Island, Md., May 23, 1911 (P. R. Myers), 

 and Mr. Banks has shown me a specimen taken by him in the Black 

 Mountains of North Carolina, in May. 



The species of this group with the disk of the squamae hairy may be 

 tabulated as follows : 



1. Eyes hairy; hind femora of female dark to beyond middle; first 



abdominal segment entirely dark . . . ., torvus 0. S. 



Eyes bare ; bases of femora yellow in female ; sides of first ab- 

 dominal segment yellow 2. 



2. Sides of mesonotum bright yellow ; legs of both sexes bright yel- 



low except for a dark band on hind femora just beyond 



middle knabi n. sp. 



Sides of mesonotum but little paler or concolorous with dorsum ; 



bases of femora dark in males 3. 



* Brit. Flies, VIII, p. 368, 1901. 



t Bull. No. 31, Ohio State Univ., p. 86, 1913. 



