Aphiochaeta. 415 



but are always visible to some degree; the very short hairs a little 

 longer at the hind margins of the segments; venter yellow, its apical 

 part not so densely bristly as in halterata, though distinct hairs are 

 seen. Hypopygium somewhat small, black or greyish black, with one 

 conspicuous bristle below on each side; ventral plate short, rectangular, 

 whitish or yellow; anal tube short, yellow. Legs yellow or pale yellow, 

 hind femora brownish just at apex, with sparse, slightly longish 

 hairs below the basal half ; bristles on hind tibiæ small, but distinct. 

 Wings yellowish, veins yellow or pale brownish; costa about 0,42 

 of the wing-length, costal divisions about as 11 — 4 — 3; third vein a 

 little thickened; costal cilia long; fourth vein very slightly curved in 

 its first part, curved upwards towards the end and slightly recurved 

 at apex, Halteres pale yellow. 



Female. Similar; frons often reddish; antennæ a little smaller 

 than in the male; abdomen without the characteristic pale colouring. 



Length 1,2 — 1,7 mm. 



Tilis species is in the male known by the hypopygium and the 

 curious colouring from halterata and fiiscohalterata^ and the female 

 is known from halterata by the longer costa and other costal divisions, 

 but from the female of fiiscohalterata I cannot satisfactorily distin- 

 guish it. 



A. palidizona does not seem to be rare in Denmark; Copenhagen, 

 Ermelund (the author), Holte, Hillerød (Th. Mortensen), Tisvilde, 

 and on Bogø south of Sealand (the author); my dates are ^Vs — ^Vs in 

 1916 to 1919. It was sometimes taken indoors on windows. 



Geographical distributions :— Hitherto only known from Denmark. 



151. A. albicaudata Wood. 



1910. Wood, Ent. Month. Mag. 2, XXI, 245, 247 {Phora). — 1914. Brues, 

 Bull. Wisc. Nat. Hist. Soc. XII, 111. 



Male. Frons broader than high, black, a little greyish and dull; 

 bristles strong, inner bristle of lower row almost not below the outer, 

 nearer to it than to the upper supraantennal; supraantennal bristles 

 rather large, equal or nearly, the upper approximate, a little nearer 

 together than the inner bristles of middle row, the lower still more 

 approximate. Antennæ of ordinary size, black, arista quite short- 

 pubescent. Palpi yellow, of ordinary size, the bristles somewhat long. 

 Thorax black, sometimes a little brownish, very slightly shining, 

 with dark brown pubescence. Pleura more or less brownish anteriorly. 



