GYMNOPTERNUS. 95 



Observation. It is remarkable that the circle of short thorns on 

 the tip of the abdomen of the female, which belongs to allied spe- 

 cies, is wanting here. This species, however, cannot be located 

 in any other genus ; on the contrary, it coincides most perfectly 

 in all other respects with the species of Gymnopternus. 



2O. G. detoilis LOEW. and 9 . Viridis, modice nitens, facie et 

 fronte cinereo-pollinosis, antennis rufis apicem versus nigris, coxis pedi- 

 busque pallide flavis, alls ex flavo ciuereis, laraellis hypopygii parvis, 

 pallide flavescentibus. 



Green, moderately shining ; face and front grayish-dusty, the red antennae 

 black at the tip ; coxae and feet pale-yellow ; wings yellowish-gray ; the 

 small lamellae of the hypopygium pale-yellowish. Long. corp. 0.12. 

 Long. al. 0.12. 



STN. Gymnopternus debilis LOEW, Neue Beitr. VIII, 35, 19. 



Green, only moderately shining ; face covered with white-gray- 

 ish, front with yellow-grayish dust. Antennae red, of middle size ; 

 third joint quite distinctly hairy, at the tip black-brown and pro- 

 vided with a sharp angle ; arista with a short, but distinct pubes- 

 cence. As far as I can perceive, the ciliaa of the inferior orbit 

 are black. The upper side of the thorax, on account of some 

 yellow-grayish dust, rather dull. The scutellum seems to be 

 bare. Yenter not yellow. Pleurae wholly gray, without yellow 

 posterior margin. Coxa? and feet pale yellowish. Tarsi towards 

 their end a little infuscated. The usual row of bristles on the 

 upper side of the fore tibiae rather prominent. Cilia of the tegu- 

 laa black. Wings only with a slight yellow-grayish tinge. Third 

 and fourth longitudinal veins towards their end almost entirely 

 parallel. The small lamellce of the hypopygium are pale-yellow- 

 ish and fringed with little black hairs. 



Hob. Pennsylvania. (Osten-Sacken.) 



Observation. G. debilis can easily be distinguished from 

 G. opacus by its smaller size and smaller antenna? ; likewise 

 from G. crassicauda by not having a yellow venter and the pos- 

 terior margin of the pleurie not being yellow. From G. politus 

 it differs by a more light-green color, less brightness, smaller size, 

 &c. &c. 



G. crassicauda LOEW. and 9 Viridis, modice nitens, an- 

 tennis rufis apicem versus fuscis, pleurarum margine postico, ventre, 

 coxis pedibusque pallide flavis, hypopygio maris valde incrassato. 



