503 Syrphidae. 



until 1886, tliough it has also affinities to Milesia. Head short, as 

 broad as thorax, behind it is excavated above; in the male the eyes 

 touching for a short distance. Frons prominent, bare. Epistoma 

 somewhat hollowed below the antennæ, with a slight central knob 

 and slightly retreating below it, it is thus a little arched, not pro- 

 minent, but somewhat descending; it is yellow with the lower lateral 

 parts black, sometimes the middle stripe darkened, and it is bare with 

 only slight hairs just at the eye-margins, Thorax a little rectangular; 

 scutellum black without marginal fringe below. Abdomen elongated 

 oval, broadest about the middle and here a little broader than thorax. 

 Legs simple, hind femora not thickened ; the legs short-haired, only 

 anterior femora with a litttle longer hairs behind. Wings with the 

 medial cross-vein sloping; no stigmatical cross-vein; basal part of the 

 radial vein with very fine hairs. 



The developmental stages are not known, but Verrall notes that 

 the female has been observed depositing eggs on exsuding sap on 

 beech and oak. 



The genus is distinguished from Criorrhina and Pocota by the 

 different epistoma and the slighter pubescence, from the former also 

 by the touching eyes in the male, and from the latter by the descending 

 epistoma with a central knob.^ The Danish species is easily located 

 by its colour. 



Of the genus one species is found in the palæarctic region, also 

 occurring in Denmark. 



1. C. faUax L. 



1758. Linn. Syst. Nat. X, 592 et 1767. XII, 2, 985, 35 et 1761. Fn. 

 Suec. 1802 {Muscu). — 1781. Fabr. Spec. Ins. II, 426, 26 (Syrphus) et 

 1805. Syst. Antl. 190, 10 {Milesia). — 1822. Meig. Svst. Beschr. III, 235,9. 

 Tab. XXIX, Fig. 10 {Milesia). - 1843. Zett. Dipt. Scand. II, 860, 6 {Milesia). 



— 1862. Schin. F. A. I, 350 {Criorrhina). — 1901. Verr. Brit. Fl. VIII, 

 590, 1, fig. 406. — 1907. Kat. palåarkt. Dipt. III, 126. — Syrphus semirufus 

 Fabr. 1794. Ent. Syst. IV, 301,85 et 1805. Syst. Antl. 243, 51 {Eristalis). 



— 1817. Fall. Dipt. Suec. Syrph. 51, 3 {Eristalis). 



Male. Vertex black, somewhat long, frons black, shining, with a 

 longitudinal middle groove, very narrowly white pruinose at the eye- 

 margins; epistoma yellow, slightly whitish pruinose at the sides, with 

 a broad, bare middle stripe, which may sometimes be darkened to 

 blackish, the lower side parts black. Vertex with black hairs, frons 

 and epistoma bare, the latter only with slight, pale hairs just along 



' Both Wiliiston and Verrall saj' in the generic description "proboscis short", but 

 the proboscis is not shorter than in Criorrhina. 



