182 ERNEST A. BACK. 



of the metanotum polished; abdomen polished, a pair of small gray 

 pruinose spots on the second and third segments; sides of abdomen 

 and the venter yellowish-gray pruinose; wings hyaline." 



Type. — U. S. N. M., Cat. No. 7948. A single female specimen. 

 Habitat.— Wash. (Prof. 0. B. Johnson). 



Ablautus rufotibialis n. sp. 



Black, brownish-gray pruinose; on the front, occiput, sides of thor- 

 acic dorsum, on the pleurae and metathorax, more grayish-white, and 

 in some lights, almost silvery white pruinose; mystax without any 

 black hair on the oral margins; tibia; and hind tarsi reddish, not black; 

 abdomen with three rows of black spots. 



I have three females from Ysleta, Texas, which are quite closely 

 related to mimus, but differ in being some larger, and all the tibiae are 

 yellowish-red, except at the extreme base and tip, as also, in part, are 

 the hind tarsi and, in some cases, the other tarsi as well. The pile 

 and bristles of the entire body is characteristic of the genus, wholly 

 white, with the exception of a few yellowish bristles on the occiput 

 and thoracic dorsum. In one specimen nearly all the bristles of the 

 dorsum are yellowish. The mystax is wholly white, with no black 

 hairs on the oral margin; there are no black hairs on the basal seg- 

 ments of the antennae above as in mimus. The eyes are bronze, 

 mottled and streaked with black; there is a faint trace of this streaking 

 of the eye in one of Osten Sacken's type specimens of mimus, and it 

 may prove that this coloration has been intensified by the rather poor 

 condition of my specimens. The thoracic dorsum is more brownish 

 pruinose than the rest of the body, with a dark median, but no dis- 

 tinguishable lateral stripes; the median stripe does not appear to be 

 divided by a pale stripe or line, but is bisected by a line of short white 

 bristles. The patches of white hair and bristles on the anterior part 

 of the dorsum on either side of the geminate stripe appear more dense 

 than in mimus. Halteres reddish; the trichostical hair white. Ab- 

 domen as in mimus, the lateral spots are considerably larger; the 

 median spots are small in comparison with the lateral spots and located 

 more near the center of the segment. In all the specimens the last 

 two segments of the abdomen are greased. On the basal segment 

 there is a black median spot, but none on the sides as on the following 

 segments. Legs, including the coxae, black; the tibiae, except at ex- 

 treme base and tip, yellowish-red; the hind tarsi are likewise reddish, 

 the terminal segments being nearly black; the other tarsi show more 

 or less traces of reddish, but on the whole are more blackish; claws 

 wholly black; hair and bristles of legs characteristic, wholly pure 

 white. Wings hyaline, in certain lights milky, with deep greenish 

 and purplish reflections; veins black, the axillary and first longitudinal 

 and the others at base of wing, yellowish. 



Type. — Am. Ent. Soc. Phil. Three female specimens. 

 Habitat.— Ysleta, Texas (April 2, 1902). 



