148 Amials Entomological Society of America [Vol. XII, 



It is a predaceous insect of possible value on account of its 

 size. Other specimens from Texas and from Falls Church, 

 Virginia. 



Erax argentifrons Hine. 



Much like rapax. Front white pollinose, mystax white, legs with 

 white hair. Length 18 to 23 inillimeters. 



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

 antennae black, first two segments with white hair, beard white. Thorax 

 yellowish-brown with the usual mid-dorsal stripe darker, hairs of sides 

 almost uniformly pale, of dorsum variable between pale yellowish and 

 black; wings hyaline, legs black, except the extreme bases of the tibiae, 

 which are reddish-yellow, clothed with pale hairs and black bristles. 

 First two segments of the male abdomen colored like the thorax, seg- 

 ments three to seven inclusive silver white, apex of two, all of three and 

 four with long white hair parted at the middle and directed outward, 

 hypopygium much narrower than in stramineus, clothed with black and 

 white hair and distinctly notched at the apex. Figure 35. 



Female abdomen uniformly yellowish pollinose and clothed with 

 pale hairs, oviduct about four millimeters in length, equivalent to the 

 last three abdominal segments. 



Specimens of both sexes taken in Clark County, Kansas, 

 by Dr. F. H. Snow. 



As has been stated, the species has much the appearance 

 of rapax, but the somewhat stouter form, the white mystax 

 and beard and much slenderer hypopygium designate it as 

 wholly distinct from that species. 



Erax plenus Hine. 



A large, robust species, varying in length from 23 to 30 millimeters. 

 Male. Total length 27 millimeters, antennae black, style nearly twice 

 as long as the third segment, palpi black and clothed with pale yellow 

 hair, face and cheeks with abundance of pale yellowish hairs, ocellar 

 bristles and several bristles on the upper part of the occiput black. 

 Thorax yellow pollinose with most of the hairs and bristles black; 

 wings with a very pale yellowish tinge, costa not thickened near the 

 tip of the auxiliary vein, furcation of the third far before the base of the 

 second posterior cell and with a distinct appendage, posterior branch of 

 the third vein reaches the costa distinctly before the tip of the wing; 

 legs clothed with pale yellowish hairs and black bristles, black, except 

 the tibia which is largely reddish. First three abdominal segments 

 dark, mostly with black hair above and white hair beneath, four white 

 with long white hair parted in the middle and directed outward; five, 

 six and seven white, hypopygium dark in color, short and somewhat 

 tumid. Figure 48. 



