120 DIPTERA OF NORTH AMERICA. [PART III. 



above, and, on the anterior part of the front, is somewhat turned 

 sideways, generally also more expanded and darker. The sides 

 of the front, each of which is nearly double the breadth of the 

 median stripe, are covered with white pollen, rendered cribrose 

 by a dense punctation of pollenless dots, so that of the pollinose 

 surface, nothing but a network is left. The face, in profile, 

 projects very much in front of the eyes, and retreats very con- 

 siderably below; its intermediate portion is, as in all the species 

 of Tetanops, comparatively narrow. The antennal fovea? are 

 deep and sharply defined, shining-black, except on their upper 

 portion. Eyes rounded-oval ; cheeks very broad. The upper 

 part of the occiput is clothed with white pollen ; in the vicinity 

 of the orbits and of the edge of the vertex this pollen is likewise 

 interrupted by punctiform pollenless dots. Antennae yellowish- 

 red, the third joint, with the exception of the basal third, more 

 or less infuscated. Although the ground color of the thorax is 

 shining-black or brownish-black, it is, with the exception of the 

 humeri, concealed by a thick grayish-white pollen, sometimes 

 yellowish on the thoracic dorsum ; numerous punctiform, pollen- 

 less dots interrupt this pollen and give it a cribrose appearance ; 

 the region of the prothoracic spiracle alone is free from these 

 dots. The pollen covering the scutellum is similar in coloring 

 to that of the thorax, but it is, to a considerable extent, much 

 less thick upon its sides. The abdomen has the same color and 

 the same pollinose surface, interrupted by punctiform, pollenless 

 dots, as the thorax, but the pollen is a little less thick and the 

 punctiform dots a little larger, so that, here and there, they 

 coalesce and the ground color becomes more apparent. The first 

 segment of the flattened ovipositor is shining black, very broad, 

 rather strongly attenuated, however, towards its end. Femora 

 blackish-brown, the tip of the front ones yellowish-red to a small, 

 the tip of the hindmost ones to a greater extent. Front tibiae 

 blackish-brown, with a yellowish-red basis: middle tibiae usually 

 entirely yellowish-red or but little infuscated towards their end ; 

 hind tibia? blackish brown, with a yellowish-red basis and gene- 

 rally also the extreme tip of the same color. Tarsi yellowish-red 

 at the basis, the front ones from about the tip of the first joint, 

 the posterior ones from about the tip of the second or third joint, 

 blackish-brown. Wings of a dingy clay -yellow, almost brownish 

 in fully colored specimens, without any distinct picture ; however, 



