152 Annals Entomological Society of America [Vol. XII, 



with a slight yellowish-brown tinge; second submarginal cell distinctly 

 appendiculate, rather long, its proximal end reaching considerably 

 beyond the proximal end of the second posterior cell; no incrassation 

 of the costa in the male. Length 23 to 25 millimeters; without ovi- 

 positor 22 to 23 millimeters, with it about 26 millimeters. 



Erax argyrogaster Macquart. 



Total length 22 millimeters. Vestiture of the head pale yellowish, 

 except the palpae bristles are black, as are some of the occipito-orbital 

 bristles, legs largely red, femora black beneath only, bristles black; 

 wings yellowish, branching of the third vein just beyond the middle 

 of the distance between the small cross-vein and the base of the second 

 posterior cell, stump about the length of the basal section. Abdomen 

 largely white, first segment dark, second with a large black triangle, 

 including more than half of the anterior part of the segment, third with 

 a smaller black triangle, fourth and each following segments with a 

 narrow black mid-dorsal line which on five, six and seven is almost 

 obsolete. Hypopygium elongate, narrow and reddish in color. 



One male from Tehauntepec, Mexico, (Sumichrast). This 

 agrees well with Macquart's description. I have not sufficient 

 material to make a comparative study of argyrogaster and 

 triton, but they appear to be much alike and perhaps the same 

 species. 



Erax varipes Williston. 



Total length 22 to 28 millimeters. A rather large and robust ash- 

 colored species with pale bristles everywhere. There may be some black 

 in front of the scutellum and on the legs and in some specimens the 

 bristles of the legs are largely black, although in the material studied 

 at least a few white bristles appear scattered irregularly. Hair and 

 bristles of the whole head entirely pale, short hair on anterior part of 

 mesothorax black, scutellum with numerous pale bristles on its margin, 

 wings hyaline, furcation of the third vein much nearer the anterior 

 cross- vein than the apex of the discal cell, making the second submarginal 

 cell very long. Legs variable in color, sometimes largely reddish, but 

 usually the femora dorsally and the tibiee basally are reddish with the 

 other parts dark. Abdomen nearly uniformly gray and rather short 

 pilose in both sexes; in the male there is not much indication of the pile 

 parting at the middle and pointing outward as in most species with 

 which varipes appears to be most nearly related. From dorsal view 

 male genitalia dark reddish, basally about as wide as the seventh abdomi- 

 nal segment, sides parallel to near the middle, then rather rapidly 

 widened and rounded apically as in Figure 59. For lateral view see 

 Figure 49. Oviduct mostly black, slightly longer than abdominal 

 segments six and seven. 



