268 NOTES ON TASMANIAN DIPTERA, ETC., 



I leave the identification of 0. pygma.us until further 

 specimens are to hand, but J suspect the species will ultim- 

 ately fall to a variety of 0. flavesce7is. The abdomen of 

 pyc/mceus seems to be identical with the colour of the abdo- 

 men in dead specimens found clinging to twigs, and indeed 

 some live specimens show signs of the abdomen becoming 

 similarly discoloured. 



A pair from Launceston (in cop. ?), not included in the 

 above table, has the female with the abdomen damaged, 

 and this has a decided "re^J-brown" colour. 



The following descriptions cover my series of 0. fdvescens, 

 both male and female. 



Male. Black ; the abdomen often extensively marked 

 v^especially in large specimens) with yellow and yellow- 

 brown ; legs yellow-brown, and often stained with black. 

 Wings hyaline, veins varying from yellowish to very faintly 

 marked. 



Female. Black; the apex of the abdominal segments 

 generally conspicuously bordered narrowly white ; legs 

 varying as in male. Wings sometimes suffused with brown 

 or smoky (hyaline in small specimens), the veins h:. large 

 specimens often strongly marked. 



Female, var. aier (White). Under this name I propose 

 to include specimens with black abdomens, and without 

 trace of apical white margins. 



The chief sexual character is to be found in the shape of 

 the abdomen, where, in the male, the abdomen is distinctly 

 longer than wide. In the female the abdomen \^ scarcely 

 longer than wide, and viewed from above, the outline 

 forms almost a circle. If the apical borders of the 

 abdominal segments are present, they are light yellow in 

 the male, and white in the female. 



Length. Male, 8 mm. to 5 mm. ; female, 7 mm. to 4 mm. 



Hab. Hobart, 1 9 (type); Triabunna, 5 ^, ]8 9; 

 Maria Island, 5 ^,9 9; Wynvard, '2 <J , 9 9 ; Mole Creek, 

 1 9; Launceston, 7 ^, 13 9; Bngdnd, 1 $. 



My dates range from November 10 to February 6, and 

 without doubt this period will be considerably extended.* 



Specimens can be taken at all hours of the day, occasion- 

 ally in quantities, sitting on the underside of dead twigs of 

 trees where their inflated bodies form conspicuous objects 

 against the sky. 



*Since the nbovo was- written, I took a male specimen in Hobart 

 dated 1st October, 1916. 



