BY FREDERICK A. A. SKUSE. 129 



The insects included in this genus may be at once distinguislied 

 by their small abdomen, and inconspicuous nature of the ^ holding 

 forceps and ^ ovipositor. Their colour is usually dull and the 

 wings have a more or less distinct brown border anteriorly. 



These flies are commonly found among grass and low herbage 

 and may be known by their peculiar darting flight. 



The New Zealand species has been described by Prof. Hutton 

 (Cat. N. Zeal. Dipt. p. 16, 1881); whilst Megistocera chilensis, 

 Phil. (V. z-b. Gr. Wien, p. 617, 1865), described from S, America, 

 is, Baron Osten-Sacken informs me, a true Macromastix. In both 

 the ^ possesses long antennas. Besides these and the following 

 no others have been described. 



Table for determining the species. 



I, /J antennae about three times the length 



of a wing cos^afe, Swed. 



II. ^ antennae about the length of a wing,., Helmsi, sp.n. 



Ill, (J and 2 antennae short. 



a. Rostrum distinctly constricted be- 



fore the middle constricta sp.n. 



b. Rostrum almost straight. 



* Wings conspicuously bordered 

 anteriorly with brown, fol- 

 lowed by a narrow almost 



hyaline streak Mastersi, sp.n. 



** Wings bordered anteriorly with 



brown, paler than the stigma obscurirostris, sp.n. 

 *** Wings deeply clouded in costal 

 cell only ; the veins slightly 



clouded humilis, sp.n. 



9 



