98 [May, 



palpi alike in both sexes, rather large and armed with nmuerous bitt not very 

 long bristles ; upper supra-antennal bristles in alignment with inner bristles of 

 middle frontral row, under ones of about half the size directly below them ; 

 anal organ and hypopygium very similar in both species, but the latter in 

 simulans produced behind into a sort of prow (fig. 3) as is well shown in 

 Mr. Collin's drawings. 



DuMtalis. A very scarce species which was described from a 

 single specimen, a male, taken in Stoke Wood on the 2nd of June, 

 1904. On the 8th of June, 1910, I again took another male, this time 

 at Longtown, under the Black Mountains. 1 have also seen a female 

 which was captured by Mr. Collin at Stokenchurch (Bucks) on the 

 6th of July, 1909, which agreed in all points with the males, except 

 that the halteres were dusky yellow instead of yellow. On looking, 

 however, carefully at the males, a dusky tint can be seen round these 

 organs. 



Cuhitalis, Beck. As has already been shown, the earlier name, 

 humeralis, Zett., must take the place of cuhitalis, Beck., for Zetterstedt, 

 as shown in his Dipt. Scand., XIV, p. 6474, was acquainted with both 

 sexes and had correctly recognised their relationship. I described it 

 from Scotch specimens, given me by Mr. Malloch, who met with it at 

 Bonhill in some numbers, settled, if I remember right, on the leaves of 

 aspen. 



Bnficornis. A widely distributed, but probably not common 

 species, the females of errata, sp. n. = cilijyes. Wood, as will be shown 

 later on, often passing for it in our collections. 



Emarginata. Another scarce species, represented in my collection 

 by three males and one female. The localities and dates for the males 

 are: Stoke Wood, 18/8/06; Mainswood, 20/5/10, 25/5/10; for the 

 female, Stoke Wood, 13/9/07. The measurement of Ij mm. in the 

 text is full large, 1 mm. would be nearer the mark, and it shares with 

 paludosa the distinction of being considerably the smallest species in 

 Section B. 



Albicans and rata. They are closely allied but undoubtedly 

 distinct, and readily to be distinguished by the characters given. 

 Albicans is a spring species and never, I think, to be taken later than 

 May. It is moderately common here, but I have not seen it from else- 

 where. Bata, on the other hand, begins to make its appearance as the 

 other is going over, and thence onward to the end of the autumn, is 

 one of the commonest and most widely distributed of the species with 

 four scutellar bristles. 



