348 BULLETIN UNITED STATES GEOLOGICAL SUEVEY. 



gall on the Wild Sage {Artemisia tridentata) in Missouri. The flies issued 

 June 7 and 9. 



Observation. — The wing of this species is altogether like that of Trypeta 

 sparsa Wied. (Monographs, etc., vol. iv, tab. x, f. 13), only the color- 

 ing is darker brown ; the white dots are less dense ; there is no white 

 mark at the tip of the first longitudinal vein ; the white apical crescent 

 begins exactly at the tip of the second vein, having only a yellowish 

 Ijrolongation before it. In the male specimen, the white drops are very 

 faint, and disappear entirely in the surroundings of the fifth longitudi- 

 nal vein. 



Trypeta (Zonosema) basiolum n. sp., c? 5. — Yellow; somewhat 

 ferruginous on the thorax ; metathorax with two black spots ; wings not 

 unlike Monographs, etc., iii, tab, xi, f. 15, only the brown border on 

 the apex is prolonged anteriorly, so as to come in contact with the 

 cross-band. Length 5-6™™. 



Yellow; somewhat ferruginous on the thorax and front; antennoe yel- 

 low, reaching beyond the middle of the face; third joint elongated, its 

 upper edge straight, perhaps even slightly concave; its tip angular; 

 arista brown, yellowish at base, finely pubescent; bristles on the head 

 black ; two black spots on the metathorax under the scutellum ; they 

 are rounded in the male, larger and in the shape of a longitudinal 

 stripe in the female; a small black dot immediately behind the root of 

 the wing, I perceive only in the female. Abdomen brownish-yellow, with 

 black pile; ovipositor broad, inverted-trapezoidal, shorter than the two 

 last segments taken together, yellowish-ferruginous. Wings subhyaline : 

 a short, oblique, pale brown mark in the costal cell near the humeral 

 cross-vein ; a pale brown cloud in the innermost proximal end of the 

 first basal cell ; a similar pale cloud on the angular vein closing the 

 anal cell ; a brown cross-band runs from the anterior margin, covers the 

 small cross-vein, and stops short in the middle of the third posterior cell 

 without reaching the hind margin ; the anterior end of this cross-band 

 is very dark brown, and nearly fills out the interval between the ends 

 of the auxiliary and first veins ; a second cross-band begins at the distal 

 end of the marginal cell, which it fills out, except its extreme tip, covers 

 the greatcross- vein, and ends, on the posterior margin of the wing, in the 

 distal end of the third posterior cell; in the middle, between these two 

 principal cross-bands, on the anterior margin, there is a short, oblique, 

 brown streak, which bisects the marginal cell, and is prolonged as a pale 

 shadow across the submargiual; along the apex of the wing, there is a 

 brown border, which begins at the second cross-band and ends a little 

 beyond the fourth vein. 



Hab. — Brookline, Mass. (Fred. 0. Bowditch). Two specimens. 



Observation. — Meigen's tab. IS, f. 16, very nearly represents the pic- 

 ture of the wings of this species, only the cross-bauds in my species 

 are farther apart toward their end. Meigen's figure represents the 

 wing of Zonosema alternata Fall. (syn. continua Meig.), and I believe 

 that T. basiolum most likewise be placed in the subgenus Zonosema. 



