Eristalis. 409 



what large. In the female there are five normal segments, the rest 

 (fom-) hidden, the last terminating with two not quite small lamellæ. 

 Legs simple, sometimes the hind femora a little, or more thickened, 

 the hind tibiæ more or less compressed and a little curved, and with 

 the usual incurvation behind near the apex ; hind metatarsi simple or 

 somewhat thickened. The legs haired in the usual way, the hairs on 

 posterior and ventral sides of anterior femora and on anterior and 

 ventral sides of the hind femora long; the hairs on tibiæ not quite 

 short, longest behind anterior tibiæ ; hind tibiæ generally more or less 

 fringed above and below; the long, solitary, bristly hair above the 

 trochanters present and more or less distinct, generally most distinct 

 on the anterior trochanters; the scabrous spot of squamose hairs on 

 the anterior side at the base of the femora distinct. Glaws and pul- 

 viUi well developed; empodium short, spine-shaped, hairy. Wings with 

 the subcostal cell closed, and the subcostal vein distinct from costa 

 quite to its end; the cubital vein with a deep loop in the middle of 

 the first posterior cell, ending considerably before the apex of the 

 wing; medial cross-vein at the middle of the discai cell; anal vein 

 more or less dipped downwards about the middle ; a stigmatical cross- 

 vein present; vena spuria distinct, in some species very weak or al- 

 most wanting; in some species (subgenera) the basal part of the radial 

 vein with very fine, but quite distinct bristles. Alula large. The wing- 

 membrane bare. Squamulæ large, the thoracai squamula the largest 

 and somewhat inflated at the inner end towards the scutellum; the 

 thoracai squamula has long, elegantly furcately divided hairs, they are 

 branched especially at and near the base, or the basal part is flat 

 and only the outer half divided into hairs; the alar squamula has 

 shorter but, however, rather long, curiously flattened hairs. Plumula 

 not large, with somewhat branched hairs. 



The metamorphosis is rather well known; the larvæ and pupæ 

 have often been mentioned and were already known to Swammerdam, 

 Reaumur and Linné. Larvæ and pupæ (probably of E. tenax and 

 some other species) are mentioned and their mode of life thoroughly 

 treated by Swammerdam (Bibi. Nat. II, 1738, Tab. XXXVIII, Fig, 9) 

 and especially by Reaumur (Mém. Ins. IV, 1738, PI. 20, Fig. 7, PI. 

 30 — 32 part.). Larvæ and pupæ of E. tenax are mentioned, or described 

 and figured, by Zetterstedt (Dipt. Scand. II, 1843, 662), Scholtz (Ent. 

 Zeitschr. Breslau, 1848—49, 22), Letzner (Arbeit. schles. Gesell. 1856, 

 117), Schiner (Verh. zool. bot. Gesell. Wien, VII, 1857, 391), Trybom 

 (Ofvers. Kgl. Vet. Akad. Forh. 1875, No 2, 87), Smith (Ent. Month Mag. 

 2, XII, 1901, 300), and very thoroughly by Batelli (BuU. Soc. entom. 

 ital. XI, 1879, 77, Tab. I— V), and in Miall (Nat. Hist. aquat. Ins. 1895, 



