1887.] 251 



The colour is somewhat of a blue-black, while H. dentipes has a brown tinge ; 

 the fly is also rather larger than that species, and the eyes of the male are rather 

 nearer together, being sub-contiguous. The thorax is more distinctly striped. The 

 abdomen, when viewed horizontally from behind, is entirely of a glistening white 

 colour, but shows a U'W dark tessellations when looked at from above or in front. 

 There is a longitudinal dorsal stripe, which is narrow and quite straight, and not 

 interrupted or dilated in the middle or at tlie edges of the segments, as is usually 

 the case with the stripe in H. dentipes. The legs ai'c long, the hind femora reaching 

 to the end of the abdomen. The fore femoi*a have one rather short, stout, but sharp 

 pointed tubercle or tooth beneath their anterior extremities towards the outer side, 

 and a blunt tubercle placed a little further back on the inner side of it. In H. 

 dentipes, though the species is called unidentate, there are really two teeth lying 

 close together and parallel with each other. The fore tibise are thicker and less in- 

 dentated than those in H. dentipes, and destitute of the little tuft of hair on their 

 ends, which are so characteristic of that species. The middle femora have a much 

 smaller and thinner tuft of hairs at their bases on the under and anterior surfaces 

 than those which are found in S. dentipes. The middle tibiae are armed much in 

 the same way as I have described those of H. dentipes to be in my list. The hind 

 tibiffi have no tubercle or callosity at their inner extremity, and also differ from 

 those of E. dentipes by having a group of strong bristles in the middle of their an- 

 terior or under surfaces. 



The wings ai-e brown or nigrescent at their bases, and along their front halves ; 

 the third and fourth longitudinal veins are rather more convergent than in H. 

 dentipes, the fourth especially being more bent. The external transverse veins are 

 rather more oblique and sinuous than those of H. dentipes usually are. The calyptra 

 have the scales rather larger than those in H. dentipes, the under one projecting 

 farther beyond the upper one ; they are also surrounded by a darker yellow rim. 

 The Ealteres have light stalks and brown heads. The female is unknown to me. 



I found two males of this fly at Douglas, I. M., in June, 1885, in a plantation 

 at the back of the Castle Mona Hotel, along with numerous specimens of H. dentipes. 



H. iMPEXA, Loew.* 



I found a single male of this pretty species at Windermere in June, 1884, and 

 have met with it since near Bradford ; I have also received specimens from other 

 parts of England, and at the beginning of August, 1886, captured several of both 

 sexes near Ulverston, Lancashire. 



It is a well-marked species, about 6 mm. in length, of a shining black colour, 

 with the thorax unstriped, but the abdomen with grey reflexions and a narrow dorsal 

 stripe. The eyes are bare, and contiguous in the male, the third and fourth longitu- 

 dinal veins of the wings are straight and nearly parallel. There is a peculiar grey 

 patch of very minute microscopic hairs running across the wing just in front of the 

 external transverse vein, and extending to the posterior border, this is absent in the 

 female. Another characteristic feature in this species, is the presence in the male 

 of a group of strong blunt black spines on the under surfaces, of the middle femora, 

 near their bases. 



The females are rather smaller than the males, but like them shining black. 



■• Beschreihungen Eiirop. Dipt., iii, Band, Halle, 1873. 



