144 Annals Entomological Society of America [Vol. XII, 



First segment of the male abdomen with long white hairs on each 

 side, second, third and fourth segments with long silvery hair parted 

 at the middle and directed outward, fifth, sixth and seventh segments 

 silvery white pollinose, but without long hair; hypopygium rather 

 large, from dorsal view about as wide as the last segment of the abdomen, 

 from side" view most prominent near middle above and cut off at tip 

 so as to give a truncate appearance. Figure 45. 



First seven segments of the female abdomen silvery white; oviduct 

 slender, shining black, about seven millimeters in length. 



Several specimens from the Huachuca Mountains, Arizona, 

 July 28, 1907. 



The large compact hypopygium of the male and the long 

 oviduct of the female give this species a distinct appearance 

 which makes its separation from others easy. 



Erax pallidulus Hine. 



A pale colored species with black legs and hyaline wings. The 

 male has the hypopygium small and, from dorsal view, very narrow. 

 Total length 18 to 2S millimeters. Mystax very pale yellowish, beard 

 white, palpi black with white hair, occipito-orbital and ocellar bristles 

 mostly black; thorax dorsally pale yellowish gray with short black hair 

 anteriorly and black and white bristles and hairs posteriorly, scutellum 

 with pale hairs and bristles, legs black, except bases of tibiae, which are 

 jDale, wings hyaline. Male abdomen silver white, first four segments 

 with long white hair, two, three and four with hair parted at the middle 

 and directed outward, five, six and seven without long hair, hypopygium 

 small, black, narrowed toward apex where, from lateral view, it appears 

 nearly evenly rounded. Figure 44. 



Female colored like the male. Oviduct black, only slightly longer 

 than the last two abdominal segments. 



'to^ 



Three male specimens and a female from Albuquerque, 

 New Mexico, collected by J. R. Watson, and one female from 

 Colorado. 



The short hypopygium and oviduct are characteristic of 

 this species. 



Erax argyrosoma Hine. 



Body nearly uniformly white all over, mid-dorsal stripe of the 

 thorax not plainly marked. Length 23 to 25 millimeters. Mystax 

 and beard white, palpi black with white hair, some of the occipito- 

 orbital bristles black and some white; legs black except the basal parts 

 of the tibife, which are yellowish haired, wings hyaline; anterior part 

 of the dorsum of the thorax with short black hair; posterior part and the 

 scutellum with black and white bristles and hairs. First four abdominal 

 segments of the male with long white hair; on two, three and four, 

 this is parted at the middle and directed outward, segments five, six 



