226 NORTH AMERICAN TRYPETINA. 



are, likewise, sulphur-yellow. The very short pile on the thoracic 

 dorsum is pale yellowish, towards the posterior corners only it 

 assumes a blackish tinge or at least a blackish appearance. The 

 black macrochastse of the thoracic dorsum are similar, in number 

 and position, to those of the three preceding species. Scutellum 

 sulphur-yellow, with four macrochaBtse on the margin. Meta- 

 thorax brownish-black, with a clay-yellow longitudinal stripe in 

 the middle of its superior margin. Abdomen on the 2d, 3d, and 

 4th segments with a transverse band near the anterior margin ; 

 that of the second segment is entire and occupies only one-half 

 of its length; those of the third and fourth segments are narrowly 

 interrupted in the middle and cover a little more than the ante- 

 rior half of the segment; the fourth segment is hardly longer than 

 the preceding two, taken together. Hypopygium clay-yellow. 

 The pile on the abdomen is blackish, and yellowish only on the 

 upper side of the first and on the pale-colored portions of the 

 upper side of the second segment ; in a reflected light, the pile on 

 the whole abdomen assumes a paler hue ; the rather weak bristles 

 at the end of the last segment are black. Feet clay-yellowish ; 

 the pile and bristles are similar to those in the three preceding 

 species. Wings hyaline, with a rather dark-brown picture ; it is 

 not quite as brownish-black as that of T. serpenlina Wied. figured 

 on Tab. XI, f. 25, but it is more like it than any other species to 

 me known. In order to form an idea of the picture of the wings 

 of T. tricincta, let us represent to ourselves that the whole outer 

 costal cell in that figure is rather hyaline, that the regions figured 

 in gray are yellow and those represented as black are dark brown ; 

 that the S-shaped rivulet, beginning at the basis of the third 

 posterior cell, running towards the anterior margin, and ending 

 at the apex of the wing, is, upon its latter half, at least one- 

 half broader than represented ; that the band beginning at the 

 posterior margin and covering the posterior crossvein is also 

 broader than represented in the figure, and this in such a man- 

 ner, that its side, looking towards the root of the wing, is a little 

 less concave ; finally, add to this picture a little streak of a satu- 

 rate brown, beginning at the posterior margin and reaching some- 

 what beyond the fourth longitudinal vein (at the very place where 

 Tab. XI, fig. 22, shows a similar streak, reaching only as far as 

 the fourth longitudinal vein). 



