136 DIPTERA OF NORTH AMERICA. 



the interior of which are a little longer that the exterior ones. 

 Coxae and femora black, covered with light-gray hoar ; the tips 

 of the latter brownish-yellow. Tibiae and tarsi rather pale brown- 

 ish-yellow, the hind tibiae with a broad, the middle and fore tibiae 

 with a narrow blackish-brown ring, which is sometimes wanting ; 

 the last joint of the tarsi brownish. In the male, the middle 

 femora, on the under side, are beset with short, but very thick, 

 black hair, the middle tibite on the under side fringed with very 

 close, short, black pubescence. Wings grayish, proportionally 

 long and narrow ; veins brown ; the second segment of the costa 

 nearly thrice as long as the third. 



Halt. Middle States. (Osten-Sacken.) 



3. N. vittata LOEW. 9 Fusca, facie laete ochracea, antennarum 

 articuli tertii basi sordide rufa ; thoracis vitta lateral!, pleurarum supe- 

 riore scutellique margine laterali obscure brunneis, abdoinine macularurn 

 nigrarum seriebus quatuor picto, femoribus nigris, tibiis late nigro-annu- 

 latis. 



Brown ; face bright ochraceous, third joint of the antennae dull red at the 

 base ; a longitudinal stripe on each side of the upper side of the thorax, 

 a longitudinal stripe on the pleurae and the lateral border of the scutel- 

 lurn dark-brown ; abdomen with four rows of black spots ; femora black, 

 tibiae with a broad black ring. Long. corp. 0.16. Long. al. 0.18. 



The most robust among the known North American species. 

 Face of middle breadth, rather bright yellow. Palpi yellow. An- 

 tennae black, third joint at its base dull red for a considerable dis- 

 tance. Front, thorax, and scutelluin dusted with brown. The 

 upper side of the thorax has on each side, near the lateral border, 

 a broad, well-defined, dark-brown stripe, and, moreover, on its 

 middle, some much less distinct brown longitudinal lines. Pleura 

 grayer than the upper side of the thorax, above with a broad, 

 dark-brown, longitudinal stripe, running from the shoulder to the 

 base of the wing, and another incomplete brown longitudinal stripe 

 immediately above the longitudinal suture. Lateral border of the 

 scutellum blackish-brown. Upper side of the abdomen dusted 

 with gray and having four rows of black spots, those of the two 

 interior rtfws being longer and more triangular, those of the exte- 

 rior rather shorter and more trapezoidal. Femora black; tibiae 

 and tarsi yellowish, the former with a broad brownish-black fascia, 

 which, on the anterior tibiae, leaves only the base and tip free ; the 

 tarsi, on account of their hair, appear darker than they really are. 



