PANTAKBES. 153 



half. The venation differs from that of Mulio obscurus in the first posterior cell being 

 closed ; from that of Callostoma fascipennis, Macq. (cf. Trans. Ent. Soc. Lond. 1881, 

 1. 14. f. 1), by the presence of three submarginal cells ; and from both in the greater 

 curvature of the ends of the second and third veins (resembling in this respect Ploas 

 and Lordotus). 



Of the two species described below, P. pusio is the only one yet known to certainly 

 inhabit our country ; the other, P. willistoni, I have no doubt will eventually be found 

 within our northern boundary, as well as in Arizona, and have accordingly for this 

 reason included it here. 



1. Pantarbes pusio, sp. n., s ? . (Tab. III. figg. 15, 15 a-d, 6 .) 



Body greyish-black, covered with white hairs below and greyish- white hairs above ; wings hyaline. 

 Length 4'5-7 millim. 



Hah. Mexico, Northern Sonora (Morrison). 



Front, lower part of the head, and occiput densely clothed with snow-white pile ; 

 upper part of the front and the ocellar eminence beset with black hair ; in the female 

 the sides of the very broad vertex beset with brown hairs; black hairs near the 

 orbits and on the ocellar eminence ; the middle of the face showing a stripe of pale 

 brownish hairs, only a trace of which is sometimes perceptible in male specimens; 

 antennae and proboscis black. The upperside of the thorax and abdomen has a covering 

 of short, semirecumbent white hairs, not dense enough to conceal the ground-colour ; 

 between these hairs there are on the thorax some longer, erect ones, partly whitish, 

 partly brownish ; on the abdomen, along the hind margin of each segment is a row of 

 long, erect, blackish or brownish hairs (distinctly visible from the side). Halteres 

 yellow. Legs : the black ground-colour, sometimes yellowish at the base of the femora 

 and on the tibiae, almost concealed under a covering of white scales. Wings hyaline, 

 slightly yellowish at the root ; veins black. Twenty ( 6 $ ) specimens. 



N.B. — P. pusio is abundantly distinguished from the North -American P. capito by 

 its much smaller size, the hyaline wings, the rows of long dark hairs on the abdomen, 

 .&c. The front in the male is proportionally narrower, in the female, on the contrary, 

 broader than in the corresponding sexes of P. capito. 



2. [Pantarbes willistoni, sp. n., s . 



Body black, with a metallic bluish reflection ; covered with black hairs on the abdomen and pale brownish ones, 



mixed with black, on the head and on the front of the thorax. 

 Length 7-8 millim. 



Hah. Noeth Ameeica, Arizona (Williston). 



Head with the tuft of hair covering the front part pale brownish ; darker, almost 

 black hairs prevailing along the edges, especially on the front ; on the vertex a tuft of 

 brownish hairs, mixed with black ones. Antennae black. The hairs on the thorax 



biol. cente.-amee., Dipt., January 1887. x 



