132 DIPTERA OF AUSTRALIA 



Erichson "luteous," and Jsennicke "rust-yellow." One author 

 says that the thorax has " four reddish lines," whilst another, 

 only noticing the interstices of these, states " three pale lines." 

 Westwood in describing his M. dimidiata says " thorace interdum 

 obscurius bivittato," which is also true of some specimens before me ; 

 all four stripes or perhaps only the two short lateral ones being 

 subject to obliteration. Osten-Sacken (Studies T., p. 186), truly 

 remarks that the thorax of M. ornatus, Jjen., appears " larger and 

 more gibbose than usual," but the specimen from which the 

 description was drawn is evidently a large, well-developed one, of 

 which I have several. With regard to the palpi, authors differ ; 

 what Walker, perhaps carelessly, calls " black " (as they seem only 

 rarely entirely black), others call " blackish-brown, yellow at the 

 base," " brownish, yellow at the base " or even " yellow, black at 

 apex." All agree in the colours of the antennae, abdomen and 

 legs, only differing in the terms employed to denote them. The 

 size of the insect is variously stated, but then among the speci- 

 mens before me there are those which will answer to each case ; 

 whilst the length of the male antennte which is only noticed by 

 Schiner (at 24 lines) varies in length from 22 to 30 lines with 

 almost imperceptible intermediate gradations. 



II. (J antennce about the length of a wing. 



427. Macromastix Helmsi, sp.n. (PI. v., fig. 22.) 



$. — Length of antennae 0-52.5 inch .. 13-32 millimetres. 



Expanse of wings 0-540x0-120 ... 13-70x3-04 



Size of body 0-380x0.070 ... 9-64x1-77 



9. — Length of antennae 0.060 inch ... 1-54 millimetres. 



Expanse of wings 0-540x0-120 ... 13-70x3.04 



Size of body 0-380x0 070 ... 9-64x1-77 



Head greyish-brown, more or less ochreous or fulvous ; frontal 

 gibbosity considerably more distinct in ^ ; rostrum brownish- 

 fulvous, sometimes tinged with blackish above and beneath ; 



