GYMXOPTERNUS. T5 



shining. Face white. Antennae black ; the inferior edge of the 

 first joint red or reddish-brown, which, however, is not distinctly 

 perceptible in some specimens; third joint short; arista, with it 

 hardly perceptible pubescence. Cilia of the inferior orbit white. 

 Front green. Abdomen with remarkably distinct black incisures. 

 Fore coxa? whitish-yellow, only at the extreme basis somewhat 

 blackened ; their front side is beset upon its basal half with numer- 

 ous black, very delicate and rather sparse hairs. Middle and hind 

 coxae black, only at the extreme tip somewhat yellowish. Feet 

 yellowish. Hind femora before the tip with a bristle. Fore and 

 middle tarsi blackened from the tip of the first joint ; still the 

 whole first joint is also somewhat dusky. Hind tibiae with a black 

 tip ; hind tarsi entirely black. Cilia of the tegula? black. Wings 

 grayish ; fourth longitudinal vein only with a slight flexure and 

 towards its end somewhat more than usually converging with the 

 third longitudinal vein. 



Male. Lamella? of the hypopygium of medium size and of a 

 rounded-ovate form, white ; on the upper and apical margin with 

 a rather narrow black border, on the latter jagged and fringed 

 with black bristles ; hind femora ciliated with moderately long and 

 very delicate pale hairs. Hind tibia? slender, plain, upon their 

 hind side without glabrous stripe. Fore tarsi plain, about once 

 and a quarter the length of the tibia? ; their first joint is longer 

 than the two following, but somewhat shorter than the three 

 following taken together. Costa at the tip of the first longitudi- 

 nal vein with a very short but distinct swelling. 



Hab. Trenton Falls, N. Y. (Osten-Sacken.) 



Gen. III. GYMXOPTERNUS. 



The following characters of the genus Gi/mnopternus are to be 

 observed: The first joint of the antenna? is hairy upon the upper 

 side, the third almost never remarkably elongated; arista dorsal. 

 The hypopygium is entirely disengaged, the exterior appendages 

 are lamelliform and of moderate size. The first joint of the hind 

 tarsi is shorter than the second and not provided with bristles. 

 The third and fourth longitudinal veins of the wings are parallel 

 or almost so. 



The last of these characters is applicable to all the North Ame- 

 rican species of Gymnoptemus known to me. Among the specie-. 



