Helophilus. 449 



— More or less narrow and smaller species with narrower 



lines on thorax 9. 



7. A row of black hairs behind the upper eye-margin; hind 

 femora in the male with a process below near base, 



bearing a bundle of black, bristly hairs 5. frutetorum. 



— No black hairs behind the eye-margin; male with no 

 process below hind femora 8. 



8. Front tibiæ not with black apex; epistoma less pro-, 

 truding than the antennal prominence; the grey lunule 

 on first abdominal segment not, or not broadly divided 

 in the middle; hind femora in the male with a tuft of 



reddish hairs below near base 6. versicolor. 



— Front tibiæ with the apex black; epistoma with the 

 mouth edge as much or more produced than the antennal 

 prominence; the grey lunule on first abdominal segment 

 broadly divided in the middle; hind femora in the male 



without a tuft of longer hairs below near base 7. consimilis. 



9. Epistoma very much produced, pointed and snout-like. . 10. lineatus. 



— Epistoma much less produced, not pointed 10. 



10. Abdomen in the male not very narrow; abdominal spots 



moderately lunulate 8. lunulatus. 



— Abdomen in the male very narrow; abdominal spots 



deeply lunulate 9. transfugus. 



1. H. trivittatus Fabr, 



1805. Fabr. Syst. Antl. 235, 15 (Eristalis). — 1822. Meig. Syst. Beschr. 

 III, 373, 5, p. p. ?. — 1843. Zett. Dipt. Scand. II, 679, 3 et 1849. VIII, 

 3123, 3. - 1862. Schin. F. A. I, 340. — 1901. Verr. Brit. Fl. VIII, 526, 1, 

 figs. 360 — 361. — 1907. Kat. palaarkt. Dipt. III, 109. — 1910. Beck. Berl. 

 ent. Zeitschr. LV, 216, 225. — H. camporum Meig. 1822. 1. c. 111, 372, 4. 



— 1846. Loew, Stett. ent. Zeitg. VII, 168, 13. 



Male. Vertex duUish, black above, the rest and the frons yellow 

 pruinose, above the anlennæ a shining, reddish triangle; epistoma 

 yellow pruinose with a bare, shining, yellow middle stripe, nar- 

 rowed upwards, the mouth edge and lower side parts black. Vertex 

 and frons yellow-haired with a black-haired cross-band above on the 

 black part; epistoma with long, yellow hairs. The epistoma is hol- 

 lowed just below the antennæ and then produced to a moderate 

 central knob, lying rather high; below the knob it is not retracted 

 but straight to the mouth edge, and it is only slightly descending; 

 jowls grey pruinose. Occiput greyish white pruinose but above black 

 towards the eye-margin; the hairs are white below, yellow above. 

 Antennæ black, third joint roundish; arista brownish yellow. Thorax 

 black, dull, with two longitudinal, grey stripes and with side margins 

 greyish yellow; it is clothed with yellow hairs. Scutellum brownish 

 yellow, paler at the margin, with yellow hairs and often black hairs 



29 



