160 DIPTEEA OF NORTH AMERICA. [PART II. 



Description of the Species. 



I. THE EYES OF THE MALE CONTIGUOUS UPON THE FRONT. 

 1. I>. opacus LOEW. . Totus niger, tibiis piceis. 

 Entirely black, tibiae pitch-brown. Long. corp. 0.12. Long. al. 0.12 



0.13. 



I 



SYN. Diaphorus opacus LOEW, Neue Beitr. VIII, 56, 1. 



Male. Entirely black. Face with the palpi and the proboscis 

 black, entirely glabrous. Antenna? black ; third joint small ; posi- 

 tion of the arista more subapical than dorsal. The eyes are com- 

 pletely contiguous on the upper part of the front ; immediately 

 above the antennas a brownish-black, opaque, triangular spot lies 

 between them. Upper side of the thorax and of the scutellum 

 covered with brown dust and opaque. The dust upon the black 

 pleurae is more gray-brown and less distinct. The abdomen 

 shining black, covered with black hair ; the stronger bristles on 

 the posterior part of the hypopygium very striking ; its exterior 

 appendages very small, black ; coxae and femora black and with 

 black hair ; fore and middle femora on the under side with a row 

 of sparse, erect, not very long black hairs ; on the under side of 

 the hind femora there are similar black little hairs, which are less 

 erect and somewhat longer only towards the end. Fore and mid- 

 dle tibiae more yellowish-brown; hind tibise dark-brown. Fore 

 tarsi slender, the first joint as long as the following three together; 

 a great part of the first joint is yellowish-brown, its tip with the 

 rest of the joints black-brown ; pulvilli not very much enlarged 

 and only moderately elongated. Middle tarsi black-brown with 

 yellowish-brown basis ; hind tarsi entirely black-brown. Halteres 

 and tegulaa black ; the cilia of the latter also black. Wings smoky- 

 blackish, towards the anterior margin darker ; they become visi- 

 bly broader towards the basis ; posterior transverse vein but little 

 before the middle of the wing ; the first longitudinal vein reaches 

 almost as far as the middle of the anterior margin and is some- 

 what distant from the latter. 



Hob. New York. (Osten-Sacken.) 



Observation 1. D. opacus is very closely allied to the Euro- 

 pean D. nigricans. As I have only one specimen of the former, 

 I am unable to prove the coincidence of both species in all the 



