296 DIPTERA 
7. Thorax without discal bristles, itshairs pale ;. 520. 00025. 2 X EOUISUL  LULN 
Thorax with discal bristles, including one posthumeral . . . DE dece UE Dire edm 
8. Scutellum with two bristles ; second antennal joint minute; legs iw Cu. BREVICORNIS, Meijere. 
Scutellum without bristles; second antennal joint equal to the third ; 
femora brown . . . sl. 2v.»  OGHSINCANA, Walker, 
9. Costal hairs short; middle tibis with extensor | brislle 05 05 5 5. a — CH. SPECULIFERA, Walker, 
Costel hairs ODE ^... 0 0 0829. UL NEIN 5 cup cd TN 
10. Middle tibize with two, hind tibize with seven extensor belles: bui: 
DAGLI ct Cu. Houcun, Melander. 
Middle tibiz without T extensor bristios, hind tibia vith iw: bin 
pslé . . 7 2... ov o4 n o rU uu m 
Geographical distribution. 
1. Ch. arenaria, Haliday, Ent. Mag. London, Vol. 1, p. 161 [1833] (Tachy- Europe. 
fesa); Walker, ibidem, Vol. 3, p. 180 [1835] (Tachypesa); List 
Dipt. Brit. Mus. Vol. 3, p. 507 [1849] (Tachydromia); Ins. Brit. 
Vol. 1, p. 138 (1851); Lundbeck, Dipt. Danica, Vol. 3, p. 281, 
f. 129 (1910). j 
brevipennis, Zetterstedt, Fauna Ins. Lappon. p. 548 [1838] (Tachyjesa); 
Dipt. Scand. Vol. 1, p. 323 142] (Fochyjósa); ibidem, Vol. 13. p. 4996 
[1859] ( Tachypeza). 
2. Ch. Beckeri, nov. sp. Germany. 
imcana, Becker (not Walker), Zeitschr. Hym. Dipt. Vol. 7 p. 119 (1907). 
3. Ch. brevicornis, Meijere, Tijds. v. Ent. Vol. r, p. 177, pl. 4, f. 6, 7(1907). C. Europe. 
4- Ch. cursistaus, Zetterstedt, Vet. Akad. Fórh. Stockholm, 1819, p. 82 Europe. 
[1819] (Empis); Fallen, Dipt. Suec. Suppl. Vol. z, p. 7 [1823] 
(Tachydromia), Zetterstedt, Dipt. Scand. Vol. 1, p. 322 [1842] 
(Tachypesa); Walker, Ins. Brit. Vol. r, p. 137 (1851); Schiner, 
Fauna Dipt. Austr. Vol. r, p. 96 (1562); Lundbeck, Dipt. Danica, 
Vol. 3, p. 278, f. 127 (1910); Wahlgren, Ent. Tidskr. Vol. 31, p. 89 
(1910); Frey, Acta Soc. Sc. Fenn. Helsingfors, Vol. 37 (3), p. 75 
(1913). ; 
5. Ch. difficilis, Lundbeck, Dipt. Danica, Vol. 3, p. 280, f. 128 (1910); Frey, N. Europe. 
Acta Soc. Sc. Fenn. Helsingfors, Vol 37 (3), p. 75 (1913). am 
6. Ch. gratiosa, Becker, Mitteil. Zool. Mus. Berlin, Vol. 4, p. 41 (1908). Canary Islands. 
7. Ch. Houghii, Melander, Trans. Amer. Ent. Soc. Vol. 28, p. 206, pl. 5, EE. United States. 
f. 2, 3 [1902] (Stilfon); Aldrich, Cat. N. Amer. Dipt. p. 314 [1905] 
(Coloboneura); Melander, Ent. News, Philad. Vol. 17, p. 370 (1906). 
8. Ch. incana, Walker. Ins. Brit. Vol. r, p. 138 (1851); Strobl, Verh. Zool-- Ireland. 
bot. Ges. Wien. Vol. 59, p. 179 (1999); Lundbeck, Dipt. Danica, 
Vol. 3, p. 282 (1910). 
(1) Chersodromia Beckeri, nov. sp. Syn. : i»tana, Becker, Zeitschr. Hym. Dipt. Vol. 7, p. 119 (1907). — 
Female. Length :.3 mm. Blackish, densely overlaid with fine gray pollen, the hairs and bristles golden. Face and 
front equally broad, cheeks one-sixth the eye-height; two pairs of vertical, one of ocellar and one of preocellar bristles ; 
proboscis, palpi and antennz yellow. "Thorax with one humeral, one posthumeral, one notopleural, two supraalar, three 
dorsocentral, one postalar and two scutellar bristles, all long, slender and yellowish, acrostichal setula biseriate; sterno- 
pleurz largely shining. Legs yellowish, the tarsi a little dusky toward the end, middle tibiz with two short extensor 
bristles, hind tibize with about five extensor bristles, in two series. Wings opalescent, veins whitish, costa with long basal 
bristle, its first segment with moderately long, closely placed pale cilia, the second, third and fourth sections of the costa 
proportioned 1 : 2 : r. 
Two specimens, seabeach at Swinemünde, Baltic Sea, received from Dr. Th, Becker as i»cana. The species isa 
close relative of Houghii, which has stronger tibial bristles; the male of Howghíi lacks the extensor bristles on the middle 
tibize and has the flexor surface of this joint closely black setulose. 
