AMERICAN DIPTERA. 389 



greatly narrowed behind ; the sides slightly sinuate and the pleurse 

 partially visible from above owing to the narrowness of the dorsum. 

 Dorsum with a pair of macrochsetse at the anterior angles and a 

 shorter pair posterior to these; also a pair of anterior discal and 

 two pairs of dorsocentral ones. Scutellum very small, with two 

 bristles. Legs rather slender, especially the tarsi, spurs of four pos- 

 terior tibia? well developed. Wings short, about the length of the 

 thorax, arcuate. At about the middle the costal bristles suddenly 

 enlarge to form enormous macrochsetse, some of which are more than 

 twice as long as the wing. Abdomen without any indications of 

 segments or sclerites, except the fifth which is small with two macro- 

 chsetse and a chitinous ring extending from its posterior edges. 



Acontistoptera iiielaiideri Brues. 



1902. Brues, American Naturalist, xxxvi, 374, figs. 4, 5. 

 Fe.male.— Length 1 mm., of longest wing bristle .4 mm. Light yellow, head 

 darker, fuscous in places, the occiput irregularly lighter, a small yellow circular 

 spot at the insertion of all the macroch?etse. Antennae, palpi and lower part of 

 the head yellowish white. Thorax hut little lighter than the head ; wings almost 

 white, their bristles black and very conspicuous, about ten in number. Legs finely 

 black hairy, more deeply colored distally. 



Eleven specimens, all from Austin, Texas, March 24th and De 

 cernber 6-7, 1901, in nests of the ant Eelton opacithorax Emery. 



XANIONOTUM Brues. 

 1902. Brues, American Naturalist, xxxvi, p. 376, figs. 6, 7. 

 Head broad, one and one half times as wide as the dorsum of the 

 thorax; rounded triangular in shape; twice as wide as long when 

 seen from above. Four macroclKetse on the middle of the front, one 

 on each side halfway toward the eye, another just in front of eve, 

 one at posterior angle, a pair of median marginal, and two widely 

 separated discal ones. Antennae attached at the lower part of their 

 unusually shallow cavities. Ocelli absent. Eyes very small. Cheeks* 

 bristly ; proboscis nearly as long as head height. Thorax rounded, 

 rather suddenly narrowed behind, much narrower than the head and 

 slightly wider than long. Scutellum very small, without bristles at 

 the anterior angles and with one pair of dorsocentral ones. Legs 

 slender, the tarsi long, tibial spurs of four posterior tarsi well de- 

 veloped. Wings nearly as long as width of thorax, band-shaped and 

 widened at apex, very strongly bristly, the costal bristles longer than 

 the wing. Abdomen with the small dorsal plate of only the fifth seg 



TRANS. AM. ENT. SOC. XXIX. DECEMBER. 1903 



