DIOSTRACUS 121 



hypopygiuni short, stout, rather disengaged ; its outer appendages 

 are small lamellae. 



The genus Diosti-ac us is so peculiar that more detailed state- 

 ments are unnecessary to distinguish it from other genera. Its 

 most striking character is the peculiar disk-like form of the palpi 

 and their very considerable enlargement in the males. 



The name of the genus (from 5t'$, twice, oarpaxuv, potsherd) has 

 reference to this character. 



1. D. prasiims Loew. % and 9- — Prasinus, subopacus, abdomine 

 nigricante, pedibus flavis, maris tertio tarsoruui anticoruin articulo com- 

 presso et in rnargine supero pilis nigris barbate 



Leek-green, somewhat dull, with a blackish abdomen and yellow feet ; 

 third joint of the fore tarsi of the male compressed and bearded on the 

 upper margin with long hairs. Long. corp. 0.18 — 0.20. Long. al. 0.23 

 —0.24. 



Sy.w Diostracus prasinus Loew, Neue Beitr. VIII, 44, 1. 



Male. Face for a male very broad, metallic-green or blue- 

 green, sometimes copper-colored, with a rather distinct transverse 

 swelling, and by far not reaching the lower margin of the eyes ; 

 dusted with grayish-yellow. Palpi of unusual size, rather rounded, 

 loosely recumbent upon the proboscis, yellow, covered on the upper 

 side with a thick snow-white powder, and with a delicate, almost 

 imperceptible, white pubescence. Proboscis for a male unusually 

 large and stout, brown. The small antennae brownish-yellow, 

 most of the third joint brown, the dorsal arista blackish-brown, 

 long and not very strong, with a short, but distinct pubescence. 

 Front above broader, metallic-green or blue-green, seen obliquely, 

 somewhat darker, without dust. Cilia of the upper orbit black, 

 of the lateral and inferior orbits yellow. Upper side of the thorax 

 of a saturate leek-green or parrot-green coloring and with very 

 little lustre; on its anterior margin there is some gray-whitish 

 pollen, which is interrupted by the anterior end of a not very 

 striking and not far-reaching dark-colored middle stripe. The 

 usual black bristles on the upper side of the thorax are I'rw and 

 slmrt ; there are no hairs upon it. If examined from behind, a Btripe- 

 like dark scarlet-brown spot, immediate])- above the root of the w ing, 

 may be noticed ; on the posterior margin of the thorax there is also 

 a more distinct covering of brown-grayish dust. Scutellum with the 

 usual bristles, otherwise bare, somewhat short, usually of a more 



