72 S. W. AVILLISTON, M. D. 



•J,, 9- — Length 20 mm. Face and front with yellowish gray dust; facial gib- 

 bosity strong, nearly hemispherical, covered with thin black and white bristle 

 and hair; the short hair on the first two joints of the black antennre is black and 

 yellowish white ; hair of the front chiefly black ; occipito-orbita^ bristles not very 

 stout, black ; beard abundant, silky-white. Dorsum of thorax with two well- 

 marked black stripes, of nearly equal width, distinctly separated by a pollinose 

 linear stripe, abruptly ending a little distance beyond the suture: on each side, 

 in front and behind the suture, two large, somewhat shining spots ; in front of the 

 scutellum a triangular spot: the pollen of thorax is gray with a slightly brownish 

 cast; hair black, moderately long in front, on the dorsum of the scutellum white; 

 bristles, thin, black. Abdomen black, a little shining; the venter and rather 

 broad lateral margins of each segment and a rather narrow hind margin of each 

 thickly gray pollinose; in the male the fifth, sixth and seventh segments silvery- 

 white; hypopygium large, black, with black hair. Legs black; tibise, except the 

 tip, yellowish red; bristles black, hair chiefly white, tip of hind tibife and first 

 two joints of the hind tarsi with golden yellow pile. Wings hyaline, costal vein 

 in the male a little thickened beyond the tip of auxiliary; furcation of third vein 

 a little distance beyond the base of the second posterior cell. 



Eah. — Atlantic and Central States. 



Erax aestnans. 



Asilus ae-ttuans "Wiedemann, Dipt. Exot. i, 20(1, 32; Auss. Zw. Ins. i, 467, 6.S. 



Erax aestuans Macquart, Dipt. Exot. i, 2, 115,19; Bigot, Eamon de la Sagra, 

 etc., 791. 



Erax rufibarbis Macquart, Dipt. Exot. i, 2, llfi, 22. 



% , 9 • — Length 15 mm. Facial gibbosity thickly covered with light yellowish 

 red hair extending nearly to the antennse, along the oral margin with a row of 

 black brjstles. Antennfe black, the first two joints with short black hair. Front 

 on the sides with black hair and on the ocellar tubercle with long black bristles. 

 Oceipito-orbital bristles black; the silky beard and the hair of the front coxae 

 abundant, light yellowish white. Thorax black, rather thickly covered with 

 brown pollen, the dorsal stripes not well defined ; bristles and hair black, the lat- 

 ter more abundant and longer along the middle of the dorsum. Abdomen black, 

 moderately shining, with rather long black hair; the venter and lateral margins 

 of the segments rather thickly brown pollinose, in the male the sixth and seventh 

 segments silvery-white; hypopygium large, black, with luteous or black pile; 

 ovipositor shining, short. Legs black ; tibiae, except the distal part, obscurely 

 yellowish red ; hair yellowish white, on the inner side of the hind tibise and on 

 the hind tarsi black; bristles black. Wings hyaline, tinged with brownish on the 

 outer end; small cross-vein near the middle of discal cell, furcation of the third 

 vein a little distance before the outer end of the discal cell. 

 3ab. — Eastern States. 



It seems evident that this species cannot be the same as Asilus aestuans 

 of Linne, as the description, '' cinereus, abdominis ultimis tribus seg- 

 meutis albis" can in no wise be applied. I do not think it expedient or 

 desirable to change the name of this, as the true aestuans may be either 

 of several of our species, and hence the name must be given up, permitting 

 U. aestuans Wied. to I'emain. 



Of the synonomy of E. rufibarbis I have no doubt whatever. 



