22 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



pyramidal projection, bearing the ocelli at its summit. Postocular cilia 

 white. Thorax light gray with a faint median brownish stripe running the 

 entire length. Bristles black, humeral bristles few in number, acrostichal 

 bristles distinct, inner dorsal bristles five in each row. Posterior dorsal and 

 lateral bristles prominent. Scutellum concolorous with the thorax, with only 

 two bristles. Abdomen subopaque with gray dust, but of a somewhat more 

 bluish tinge than the thorax. Hairs covering the segments white. Hypopyg- 

 ium long and rather thick, glabrous, black. Appendages very short, yel- 

 lowish brown. Pleurae and coxae bronze- black, dusted with gray. Bristles 

 above the insertions of the fore coxas and the hairs on the anterior surfaces 

 of the fore coxae yellow. Legs yellow, all the femora black nearly to their 

 tips. Tarsi infuscated at the tips. Hind metatarsus plain, a little more than 

 half as long as the succeeding joint. Wings slightly opaque whitish, with 

 light yellow veins. Venation normal. Distal segment of the fifth vein 

 twice as long as the posterior cross-vein. Halteres and tegulae yellow, the 

 latter with pale cilia. 



One specimen from Colfax, Washington, collected by 

 Professor J. M. Aldrich. 



The species, at least the male, is readily distinguishable 

 by the very prominent front. 



22. Medeterus aberrans, sp. nov. 

 Plate H, Fig. 40. 



Female. Length 2.75 mm.; length of wing 2.75 mm. Proboscis and palpi 

 small, piceous, the former with pale hairs. Face metallic green, bluish below, 

 golden above the suture, without dust. Antennae black, first joint broad and 

 thick, second very short; third acorn-shaped, much narrower than the pre- 

 ceding joints, pilose and bearing a very long, slender and distinctly pubes- 

 cent apical arista. Front very concave, golden green, with a center which is 

 opaque brown in some lights. Postocular cilia light yellow. Thorax, scutel- 

 lum and abdomen bright golden green. There is a layer of pale dust on the 

 scutellum and also on the prescutellar region of the thorax, which is not so 

 distinctly flattened as in the other species of Medeterus. Thoracic bristles 

 black; acrostical bristles in two rows, very distinct; humeral bristles rather 

 small, sparse, lateral and posterior dorsal large and prominent. Scutellum 

 with four robust bristles. Abdominal segments covered with light yellow 

 hairs. Ovipositor slender, yellow. Pleurae metallic green, covered with pale 

 dust. Coxae infuscated, with yellow tips and covered with pale dust. 

 Bristles above the fore coxae and on the anterior surfaces of the fore and mid- 

 dle coxae yellow. Legs yellow throughout, only the tip of last tarsal joint 

 blackish. Fore tibiae without bristles, middle tibia with a prominent black 

 bristle before the middle and two short bristles at the tip. Hind tibia with a 

 single bristle near the base and three bristles at the tip. Hind metatarsus a 

 little more than half the length of the succeeding joint, with a prominent 

 black bristle at its tip on the lower surface. Wings grayish hyaline, with a 



