174 DIPTERA OP NORTH AMERICA. [PART III. 



wise a similar one. The former are at once distinguished, how- 

 ever, by the front, which is not conically projecting. They 

 are characterized also by the shape of the wings and the vena- 

 tion, which it will be easier to understand from the figure than 

 from a description. 



1. S. tenuis LOEW. $ .(Tab. IX, f. 21.) Chalybeo-viridis, pedibua 



nigris, basi tarsorum rufa; alis cinereis, stigmate et plaga permagna 



apicali nigris. 

 Greenish-steelblue, the feet black, the root of the tarsi red ; the grayish 



wings have a black stigma and a large black spot at the apex. Long. 



corp. 0.14; long. al. 0.13. 

 SYN. Stenomyia tenuis LOEW, Berl. Ent. Zeitschr. XI, p. 321, Tab. II, f. 24. 



Front brown, almost black above, rather hairy along the orbits 

 of the eyes, upon the remaining surface only with two more 

 elongated hairs ; the little stripes running down from the vertex 

 along the orbits of the eyes and the ocellar triangle are dark 

 bluish-green, shining. Antennae black; the second joint at its 

 upper corner to a certain extent dirty-whitish ; third joint rather 

 broad, upon the upper side hardly excised, but with a sharp 

 anterior corner. Face somewhat retreating, with a distinct 

 depression under each antenna, longitudinally convex along its 

 middle, dark steel-blue, shining, but on its upper half with a thin, 

 whitish bloom. Clypeus of a very moderate transverse diameter, 

 but distinctly projecting over the upper border of the mouth, deep 

 steel-blue and shining. Palpi black. Eyes large and rather 

 round, their horizontal diameter, however, is a little larger than 

 the vertical one. Cheeks narrow. Thorax dusky blue-green, 

 rather shining, scutellum greenish-black, but little shining, with 

 an entirely even upper side. The narrow and long abdomen has 

 the same coloring as the thorax ; however, towards its extremity 

 it gradually becomes more black and opaque. Feet black; 

 femora and tibia? with metallic, dark bluish-green reflections ; the 

 extreme tips of the tibiae and the root of the tarsi are dark brick- 

 red, the remainder of the feet brownish-black. Halteres whitish. 

 Wings long and narrow, grayish, the root and a rather large spot 

 immediately behind the stigma lighter ; the rather small, narrow 

 stigma is of a black color, which extends below it as far as the 

 second longitudinal vein; the last third of the wings, beginning 

 at the costa as far as the fourth longitudinal vein, is tinged with 



