HOUGH: SOUTH AMERICAN MUSCIDi. 21 < 



can see it, and the dorsal half of the posterior orbit are pol- 

 ished metallic green. The bristles of the head show only the 

 following slight differences from those of the female of M. 

 ochrifacies Rond. : (1> The orbitals are still smaller; (2) the 

 occipito-central is smaller: (3) on the occiput, parallel to the 

 ciliip of the posterior orbit, there is but one row of bristles. 

 The antenna' are yellow, inclining more or less to brown, espe- 

 cially on the third joint. 



The thorax and abdomen are dark metallic green, blue, or 

 purple, with scarce a trace of pollinose coating whatever the in- 

 cidence of light. The abdomen has no macrochanii' even at the 

 lateral borders of the segments. The bristles of the thorax are 

 represented in figure 7. They are mostly small. The third 

 dorso-central may be absent. The discal scutellars number from 

 one to three ; occasionally one of them is nearly as large as the 

 apical and then the others are suppressed ; occasionally again 

 one of them is nearly or quite marginal. It is notable that at 

 the cephalo-ventral angle of the meso-pleura there are no large 

 bristles, but merely a clump of hairs. The legs vary in color 

 from brown to black. The tibiiv are often lighter in color than 

 tlie femora. The bristles of the femora are quite long and 

 -troug, but show no peculiar arrangement. The anterior tibia 

 has no bristles in either sex, save the usual preapical of the ex- 

 tensor border. The middle tibia is alike in both sexes : its an- 

 terior surface has no large bristles and no peculiar arrangement 

 of minute spines ; its posterior surface has near the flexor bor- 

 der one large bristle at the middle and one at the junction of 

 the basal and second fourths ; it also has near the extensor bor- 

 der on its apical third from one to three smaller bristles. Hind 

 tibia of male has on its lateral surface near the flexor border a 

 row of six or seven short, almost equidistant bristles, which be- 

 gins at about the junction of the basal and middle thirds and 

 extends to the apex ; on the lateral surface near the extensor 

 border is a complete row from base to apex of mostly small, un- 

 equal sized but almost equidistant bristles : on the mesal surface 

 near the extensor border is a not at all prominent beard of short, 

 -aft hairs which extends the whole length of the tibia, but is 

 much longer on the middle two-fourths of its extent than else- 

 where ; on the mesal surface near the extensor border there is 

 one bristle at the junction of the basal and second fifths. The 



