142 Annals Entomological Society of America [Vol. XII, 



variations occur even to the extent of having the tibiae and tarsi 

 in large measure reddish. It seems best, after considering 

 the facts to regard diibius as no more than a variety of stramineus 

 if not a synonym. 



Several specimens from Wyoming agree with the type 

 specimen of dubius. 



Erax rapax Osten Sacken. 



Total length 20 to 25 millimeters. Mystax, beard and palpal 

 hairs decidedly yellow, frontal and occipito-orbital bristles mostly black. 

 Bristles and hairs of the mesothoracic dorsum largely black, margin of 

 the scutellum with a row of many long bristles which are viarable 

 between black and yellow in different specimens. Wings yellowish 

 hyaline, furcation of the third vein much nearer the small cross than 

 to the base of the second posterior cell, stump distinctly longer than the 

 basal section. Legs black with an abundance of yellow hair, bristles 

 black, but an occasional pale one intermixed. As in stramineus the legs 

 vary in color and many specimens have the bases of the tibiae reddish 

 while others have the legs generally paler throughout. Male abdomen, 

 segments one, two and anterior part of three dark, nearly black, re- 

 mainder of three and all of four and five silvery and with silvery hairs 

 parted at the middle and directed outward, six similar but hairs shorter, 

 seven silvery pollinose. Hypopygium black with mostly black pile, 

 although more or less yellow pile is likely to be present. ' Ventrally 

 this pile is longer and more conspicuous than elsewhere. See Figure 

 41. Female generally less pilose than the male, abdomen gray pollinose, 

 oviduct shining black, somewhat longer than abdominal segments 

 five, six and seven. 



Common in southwestern United States and Mexico. 

 The type locality is Northern Sonora. 



This species is difficult to separate from stramineus in the 

 northern part of its range. 



Erax aurivestitus n. sp. 



Male. Total length 22 millimeters. All the vestiture of the head, 

 except the bristles in the region of the ocelli and one or two occipito- 

 orbital bristles on each side, distinctly yellow; head, thorax and base 

 of abdomen yellow pollinose, dorsum of the mesothorax with black 

 hairs and bristles, pleurae mostly with black hairs and bristles, but with 

 some pale ones intermixed, coxae with yellow bristles, other parts of 

 legs mostly with abundance of yellow hair and some black bristles, 

 femora black, in ground color, tibiae and tarsi dark reddish, wings 

 yellowish hyaline, furcation of the third vein distinctly before the 

 middle of the distance between the anterior cross vein and the base 

 of the second posterior cell, stump longer than the basal section. First 

 and second abdominal segments dark in color with mostly dark hairs 



