Helophilus. 445 



are short, third joint roundish, in the subg. Liops the third joint 

 higher than long with a sharp angle above; the arista apparently 

 bare. Epistoma a little hollowed below the antennæ, then produced 

 to a small central knob and from it straight down to the mouth edge, 

 not retreating except in the subg. Liops ; its lower part is thus only slightly 

 protruding and likewise slightly descending, but in lineatus it is much 

 protruding, long and snout-like, and here no central knob is visible. 

 The epistoma is pale pruinose, either with a black or yellow, bare 

 middle stripe or pruinose all over; it has longish hairs. Mouth parts 

 mainly as in Eristalis, sometimes (lineatus) the oral cone and pro- 

 boscis rather long. Thorax with two (sometimes three) grey or yel- 

 lowish, longitudinal middle stripes and with the side margin yellow; 

 in some northern species the lines on thorax are very naiTOw or 

 interrupted. Scutellum yellow or brownish, it has no distinct down- 

 wards directed fringe below the margin, only in the larger species the 

 marginal hairs are curved somewhat down. Abdomen relatively longer 

 than in Eristalis, and in the smaller species rather narrow; its number 

 of segments is in both sexes the same as in Eristalis; in the large 

 species {Helophilus s. str.) the basal ventral segments are only slightly 

 chitinised. Abdomen is marked with rather extended yellow side spots; 

 in the smaller, narrow species the markings are more restricted; the 

 markings are in so far curious as they are in most cases in reality of 

 two kinds; besides the yellow spots there are on third segment a pair 

 of small, pruinose spots in the middle in connection with or covering 

 a part of the yellow spots, and on fourth and (in the female) fifth 

 segment the spots are quite or almost quite of the pruinose kind; 

 other pruinose spots may be present at the hind margins, and in the 

 smaller, narrower species the spots are often all pruinose. The genitalia 

 are large, in some species (Girschner's subg. Parhelophilus) very large 

 and with large appendages. Legs with the hind femora considerably 

 thickened and sometimes with sexual ornamentations in the male as 

 a process or wart with hairs or bristles or as a bundle of hairs below 

 near base; hind tibiæ curved and compressed so that they have an 

 edge below; the usual incurvation behind near apex small; hind tarsi 

 often flattened, sometimes all tarsi. The legs haired about as in 

 Eristalis but the hairs not long, the hind femora more or less setulose 

 beneath; the trochanters have the same curious long hair above as 

 in Eristalis, and also the curious, scabrous spot at the base of the 

 femora on the anterior side is distinct. Wings differing from those in 

 Eristalis by the subcostal cell being open, either somewhat narrowly 

 or more or less broadly; anal vein generally dipped as in Eristalis, 

 sometimes only slightly, it is abruptly curved just at the apex; other- 



