1919] Nine: Genus Erax 123 



and seven silvery. Hypopygium shining black with abundance of 

 fine black hair; from side view notched at tip and quite different from 

 other species of its group. Refer to Figure 22. 



Holotype: Male from Clark County, Kansas, F. H. Snow. 

 Several males and females from Clark, Ellis, Grove and Ness 

 Counties, Kansas, mostly taken in July. 



The female differs from the male only in sexual characters. 

 The oviduct is distinctly shorter and stouter than in aestuans 

 and apicalis, being only about as long as the last three abdominal 

 segments. 



The species is entirely distinct and easily recognized by its 

 small size, yellow mystax and male and female genitalia. The 

 bristles at the apex of the scutellum are subject to slight varia- 

 tion in number and in some specimens are golden yellow instead 

 of black. 



Erax mexicanus n. sp. 



Male. Total length 12 millimeters. Mystax black above, pale 

 yellow below, palpi with black bristles, beard pale yellowish, wings 

 nearly uniform brownish, costal margin very slightly dilated, stump 

 of anterior branch of the third vein much shorter than the connecting 

 vein; legs black in all their parts. Abdomen black with yellow hairs, 

 segments five, six and seven silvery, venter of last abdominal produced 

 backward the length of more than two abdominal segments and with 

 several black hairs at the tip. Genitalia black, shining, tumid, suddenly 

 narrowed before the apex, produced into a distinct tubercle. See 

 Figure 27. 



Female colored like the male; stump of the anterior branch of the 

 third vein a little longer than in the, male, but not much longer than 

 the basal section. Genitalia somewhat longer than segments five, six 

 and seven. 



Male type and allotype from Tapachula, Chiapas, collected 

 by D. H. Crawford. Three other males from the same locality. 

 One male is somewhat larger than the type and has only abdom- 

 inal segments six and seven silvery. 



The small size, black legs and peculiar male genitalia serve 

 to distinguish the species. 



Erax femoratus ^Macquart. 



Total length, male and female, 26 to 30 millimeters. Mystax 

 largely black, but with white hairs intermixed, beard pale, palpi black 

 hairy, occipito-orbital bristles black; mesothoracic dorsum before with 

 very short black hair, several strong black bristles above the roots of 

 the wings and before the scutellum; scutellum with fine white hairs 



