BY FREDERICK A. A. SKUSE. 127 



>?ross-veiii ; second posterior cell petiolate ; proximal end of stigma 

 thickened. Front broad, with a tubercle anteriorly. Rostrum 

 as long as the head ; nasus distinct. Antennse 13-jointed in both 

 sexes ; ^ antennte sometimes very long and filiform, often shoi't 

 as in the 5 (about the length of, or even a little longer than, the 

 head and rostrum combined). Genitalia inconspicuous in both 

 sexes. 



Rostrum the lengtli of the head ; in M. constricta (PI. vi., 

 fig. 51) distinctly constricted just before the middle of its 

 length (viewed from above) ; clothed with minute pubescence ; 

 nasus distinct, haired. Palpi with the first and third joints 

 about equal in length, the second slightly longer, fourth 

 joint about the length of preceding taken together. The 

 antennae are 13-jointed, short in both sexes, or the ^ antennae 

 very long (of extraordinary length in M. costalis and the 

 South American M. chilensis, Phil). The great length of the ^ 

 antennae in some species has hitherto been regarded as a generic 

 character, but it is now found that, as with Mey istocera, Wied., and 

 some other genera, there are species in which both ^ and Q possess 

 short antennae. In the ^ of M. costalis the antennas are about 

 three times the length of a wing ; the first joint of the scapus 

 incrassate^ almost fusiform, the second short annular ; first nine 

 flagellar joints almost filiform, progressively increasing in length 

 and diminishing in thickness ; the terminal two joints very minute 

 (particularly the last one) ; the flagellum is clothed on the inner 

 side with a microscopic dense pubescence, amongst which, at 

 regular intervals, are minute spine-like bristles. Baron Osten- 

 Sacken says that the microscopic pubescence exists on the under- 

 side of the flagellum ; however, it is distinctly on the inner side in 

 21. costalis, and only visible viewed from above or beneath. The 

 (^ antennae of M. Helmsi are almost the length of a wing ; the 

 first joint of scapus much smaller than in M. costalis ; the flagellar 

 joints of similar structure to those of the last-named, but with 

 dense microscopic pubescence both beneath and on the inner side, 

 a more sparse pubescence above and on the outer side, and with- 

 out the spine-like bristles (as in the New Zealand M. vul^nna, 



