194 DIPTERA OF NORTH AMERICA. [PART II. 



and small. Front black with a violet, often very bright lustre, 

 immediately above the antennae with a pale copper-reddish spot. 

 The cilia on the inferior orbit pale. The upper side of the thorax 

 often shows violet reflections. The scutellum shining violet, 

 rarely shining black with an indistinct violet lustre. The color 

 of the abdomen is usually more greenish-black. Fore COXES brown- 

 ish-yellow, near the basis blackened ; middle and hind coxae black 

 with brownish-yellow tip. Feet yellowish-red or brownish-red. 

 The extreme tip of the knees blackish-brown and the tarsi from 

 the tip of the first joint black. Sometimes the upper side of the 

 femora is distinctly infuscated. Cilia of the tegulas black. Wings 

 tinged with blackish-gray and with black veins ; the convexity of 

 the wings lies before the first quarter of the last segment of the 

 fourth longitudinal vein. 



Male. Its fore femora are thickened as far as their middle, and 

 on the under side, precisely at the end of this thickening, they are 

 densely bearded with stiff little bristles ; the fore tibias are visibly 

 stouter than in the female, beset on the under side with numerous 

 and erect, on the upper side with less numerous and less erect 

 bristles ; fore tarsi with unusually long hairs, especially on their 

 first two joints. The structure of the middle femora is similar to 

 that of the fore femora, though their thickening is less strong and 

 reaches as far as the tip ; the thick beard on the under side, formed 

 of short stiff bristles, is thus brought nearer to their end. The 

 middle tibice are of rather irregular structure ; from the basis to 

 about their middle they are distinctly thickened and fringed on the 

 upper side with a few long black bristles, on the under side they 

 are provided with a small tubercle, beset with short bristles. That 

 part of the middle tibias, which is not thickened, is of a plain struc- 

 ture, though beset on the under side with a row of rather long, 

 black, bristle-like hairs. The middle tarsi and the whole hind 

 feet are of a plain structure. 



Nab. Pennsylvania. (Osten-Sacken.) 



2. C. claudicans, nov. sp. and 9 Olivaceus, facie ochracea, 

 alis infuscatis, punctum nigrum in ultimo venae quartae segmento geren- 

 tibus, coxis anticis ex testaceo fuscis, pedibus ex rufo testaceis. 



$ . Tibiis intermediis crassissiinis, varis, supra nigro-spinulosis, tarsis in- 

 termediis totis nigris, articulo prirao crasso, recurve, supra nigro-setoso, 

 tarsis anticis posticisque simplicibus, inde ab articnli primi apice nigris. 



J . Pedibus simplicibus, tarsis omnibus inde ab articuli primi apice nigrig. 



