NATUTtAL SCIENCES OP PHILADELPHIA. 225 



in the ovipositor and the smallness of the rj 1 forceps render the recognition of 

 the sexes very difficult. 



C. paradox a. Thorace livido, nigro-vittato ; antennis nigris, pedibus, basi 

 pallidis ; alis immaculatis. Length lin. 1-1. 



Head blackish ; palpi and antennae black. The color of the thorax is livid ; 

 but it is scarcely apparent between the black stripes ; intermediate stripes 

 broad, capillary ; lateral ones extended over the scutum ; scutellum pale, 

 metathorax dark ; pleurae blackish ; halteres pale ; feet clothed with hairs ; 

 coxae and base of the femora pale ; their tips brown ; tibiae brownish-tawny, 

 infuscated at tip ; tarsi likewise. Abdomen blackish (often greenish in living 

 specimens, the color depends on the food.) Wings hyaline, without apparent 

 stigma ; veins brown, costal and subcostal pale yellow ; neuration as de- 

 scribed among the generic characters ; apical areolets slightly pubescent in 

 the middle. 



Twenty-one specimens taken at the White Sulphur Spings in Va., on the 

 30th of June, 1859. 



Erioptera Meig. 



Wings pubescent on the whole surface, or on the veins only ; two radial areae; 

 mediastinal cross-veins at a considerable distance from the tip of mediastinal 

 vein, although posterior to the origin of petiole, the latter nearer than usual to 

 the origin of the wing. Antennas with 16 joints. Proboscis and palpi short. 

 Tibiae without spurs at the tip. Pulvilli distinct. Ungues smooth. 



The pubescence of the wings is the most striking character of Erioptera; 

 still it is not sufficient for defining the genus, because U 1 a and several L i m - 

 n o p h i 1 a?, have also wings which are pubescent along the veins, or on the 

 whole surface. The characters enumerated above, especially the spurless 

 tibae, complete the definition. 



Erioptera, thus defined, is far from being homogeneous, and ex- 

 hibits among a comparatively small number of species more variety in the neu- 

 ration of the wings or the structure of the J, genital organs than either L i m - 

 nobiaorLimnophila, although these genera are much richer in species. 

 It has been observed already by Mr. Curtis, (Brit. Entom. 557,) that in some 

 Eriopterae the antennae of the % are much longer than those of the female, 

 and that such species show at the same time some peculiarities in the neuration 

 of the wings, and might therefore, with good ground, be separated from the 

 rest of the genus. 



My E.hirtipennis and pubipennis belong to the group thus de- 

 fined by Curtis. My E. ch,lorophylIa,vespertina,septemtrionis, 

 villosa, chrysocoma, etc., seem to form another natural group ; my E. 

 Meigenii and u u b i 1 a a third one ; E. caloptera Say, and p a r v a nob . 

 a fourth, etc. 



The $ forceps shows a great variety of structure ; several pieces are figured 

 on the plate ; fig. 19, E. v e s p e r t i n a (one half;) fig. 20, R. a r m a t a , upper 

 side ; fig 21, the same, side view ; fig. 22, E. c a 1 i p t e ra ; fig. 23, E. venusta, 

 upper side; fig. 13 a under side. 



Analytical Table. 



1. Second radial area shorter than the cubital ; petiole ending in the cubital, 2 

 Second radial longer than the cubital ; petiole ending in the second radial ; 



first and third externomedial areolets longer than the subapical, the great 

 cross-vein being much nearer to the base of the wing than the other central 

 cross-veins, 14 



2. No discal areolet, 3 

 A discal areolet, 11 



3. Second externomedial areolet petiolated ; wings like Meig i. tab. iv. f. 9, 4 

 First externomedial areolet petiolated, 9 



1859.] 



17 



