98 DIPTERA. 



N.B. — About the remarkable resemblance between this species and Anthrax sinuosa 

 see the latter species. 



DIPALTA. 



Dipalta, O. Sacken, Western Diptera, p. 236 (1877) . 



" Differs from Exoprosopa in the course of the second vein, which is strongly con- 

 torted, in the shape of a recumbent S, near its point of contact with the cross-vein 

 which separates the first submarginal cell from the second. 



" A still more important difference lies in the structure of the antennae, the third 

 joint of which does not bear the terminal style so apparent in Exoprosopa, and is more 

 like that of the genus Anthrax. Examined attentively, that joint shows, on its incras- 

 sate, basal part, a more or less distinct transverse suture, which also exists in Anthrax, 

 and may indicate that the third joint is very much shortened here and coalescent with 

 the style, their suture being very near the base of the joint. The joint is onion-shaped 

 nt the base, with a slender, gently tapering, almost linear, prolongation, ending in a 

 point. I do not see any bristle at the end. The body is more slender than in Exopro- 

 sopa, and the hairy covering of a more uniform colour. 



" Diplocampta, Schiner (Reise d. Novara, p. 119, t. 2. f. 9), from Chili, resembles 

 Dipalta in the curvature of the second vein ; nevertheless, it is evidently different ; the 

 abdomen is not longer than the thorax, and narrower, being gradually attenuated 

 posteriorly ; the structure of the antennae is different ; the species is small (1 J to 2 lines 

 long), with nearly hyaline wings ; the position of the cross-vein between the second 

 and third veins is different." — Western Diptera, I. c. 



To this I may add that there are no pulvilli, and that the base of the ungues shows 

 an incrassation, but no tooth. 



1. Dipalta serpentina. 



Dipalta serpentina, O. Sack. Western Dipt. p. 236 \ 



Hab. United States, California, Colorado, Texas 1 . — Mexico (Sumichrast, in coll. 

 Bellardi). Two specimens. 



ARGYRAMCEBA. 



Argyrammba, Schiner, Wiener ent. Monatschr. iv. p. 51 (1860). 



Schiner established this genus on the following characters : — " A pencil of hairs at the 

 tip of the antennae ; distinct pulvilli ; the presence of a stump of a vein on the fork of the 

 third vein, and on the knee-shaped curvature of the second." The last character is very 

 generally, although not always, present ; in some American species {A. georgica, Macq., 

 A. acroleuca, Wiedem., &c.) either one of these stumps or often both are wanting. To 

 these characters may be added: — 1. The structure of the male forceps, placed symme- 

 trically with regard to the abdomen (and not unsyminetrically as in Exoprosopa and 



