Chrysotoxum. 573 



widened towards the sides, and abdomen is thus more black; it is 

 also more shining, especially towards the apex; it is haired mainly as 

 in cautum but the hairs just at the basal corners are black. Genitalia 

 small, with the appendages very much smaller. Venter black, shining, 

 with pale hind margins to the segments; third and fourth segments 

 with narrow, transverse, yellow side spots placed on the middle of 

 the segments; the hairs are long, partly yellow, partly black. Legs 

 mainly as in cautum but thinner ; the hairs on femora nearly all black. 

 Wings with the brownish yellow tinge more distinctly along the 

 anterior margin. 



Female. Vertex broader than in cautum, frons widening down- 

 wards, black, with two large, yellowish dust spots; the hairs black. 

 Antennæ longer than in the male with the third joint relatively longer. 

 Abdominal bows broader but likewise not widened towards the sides; 

 the hairs at the basal corners not black. Legs with the femora less 

 black on the basal part, hind femora nearly all yellow. 



Though similar to cautum the species will easily be known; in 

 the male the small genitalia at once distinguish it, and in both 

 sexes it is distinguished by the antennæ, the yellow spots on venter, 

 besides by other characters. 



C. arcuatum is rather rare in Denmark, I know only seven speci- 

 mens, three males and four females; Tisvilde (Klocker, the author) 

 and in Jutland at Silkeborg (Jensen-Haarup). The dates are only 



8/7 26^7^ J|- ^y^g fQy ^J^g flfg^ ^JjJJg takCU lYl 1907. 



Geographical distribution : — Northern and middle Europe down 



into Austria, Styria and Hungary; it is also recorded from Italy 



(var. nigropilosum) ; towards the north to northern Sweden, and in 

 Finland. 



3. C. festivum L. 



1758. Linn. Syst. Nat. X, 593 et 1767. XII, 2, 986, 45 et 1761. Fn. 

 Suec. 1812 (Musca). — 1856. Loew, Verh. zool. bot. Geseli. Wien, VI, 612, 9. 



— 1862. Schin. F. A. I, 255. — 1901. Verr. Brit. FL VIII, 650, 5, fig. 440. 



— 1907. Kat. palaarkt. Dipt. III, 148. — Mtisca arcuata De Geer (nec L.) 

 1776. Mém. Ins. VI, 125, 15. — 1775. Fabr. Syst. Entom. 767, 22 (Stjr- 

 phus) et 1805. Syst. Antl. 184,3 (Mulio). — 1816. Fall. Dipt. Suec. Syrph. 

 5, 2 (Mulio). — 1822. Meig. Syst. Beschr. III, 162, 2, Tab. XVII, Fig. 7. — 

 1841. Loew, Stett. ent. Zeitg. II, 138, 159. — 1843. Zett. Dipt. Scand. II, 

 636, 4 et 1855. XII, 4644, 4 et 1859. XIII, 5074, 4. — Musca Upunctata 

 O. F. Miill. 1776. Zool. Dan. Prodr. 2041. 



Male. Vertex black, more or less greyish behind; frons black, 

 yellow or greyish pruinose behind at the eye-margins; epistoma yellow 

 with a broad middle stripe and a band downwards from the lower 



