NATURAL SCIENCES OF PHILADELPHIA. 203 



Analytical Table for determining the genera. 



I. One radial area ; antennae 14-jointed ; ungues armed with teeth on the 

 under side ; tibia? without spurs at the tip ; pulvilli indistinct or none ; 

 (natural group.) Limnobia nob. 



II. One radial area; antennae 16-jointed; (*) 



(artificial group.) 



A. Mediastinal vein indistinct, being closely applied to the subcostal vein ; 



no mediastinal cross-vein apparent ; petiole, not arcuated at its 

 origin, but forming an acute angle with the subcostal vein ; anal 

 angle of the wing square. Antocha nob. 



AA. Mediastinal vein distinct ; petiole arcuated at its origin ; anal angle 

 rounded. 



B. No stigmatical cross-vein ; proboscis elongated ; palpi at its tip. 



C. Proboscis almost as long as the body. Elephantomyia nob. 

 CC. Proboscis shorter than the bod ,r but longer than tlw head. 



Rhamphidia Meig. 



BB. A distinct stigmatical cross-vein. 



D. A distinct fold, having almost the appearance of a supplementary 



vein, runs from about the middle of the anal vein, down the anal 

 area, towards the posterior margin of the wing ; no distinct stigma ? 

 proboscis short ; wings elongated. Dicranoptycha nob. 



DD. No fold in the anal area ; a distinct stigma ; proboscis elongated, 

 although shorter than the head ; collare prolonged in a narrow, al- 

 most linear neck ; wings broad, rather short, with a rounded poste- 

 rior margin, very pure hyaline ; the subcostal vein does not extend 

 much beyond the central cross-veins. Teucholabis nob. 



III. Two radial arese. 



E. Tibia? unarmed with spurs at the tip. 



F. Wings pubescent on the whole surface, or their veins clothed with long 



hairs. Erioptera Meig. 



FF. Wings naked, or only with a short pubescence along the veins. 



G. Axillary vein undulated ; (see, Meig. i. tab. v. f. 7.) Symplecta Meig. 

 GO. Axillary vein straight, or almost straight. 



H. The first radial area has the form of an almost equilateral triangle, 

 the petiole being very oblique ; 1 and $> genital organs obtuse, with- 

 out distinct horny appendages. Cryptolabis nob. 



HH. The first radial areas has its usual elongated form ; the tf genitals 

 have several distinct elongated, horny or coriaceous appendages ; the 

 ovipositor of the $ consists as usual of horny, pointed valves. 



J. The second radial area is very short, almost triangular ; the upper 

 branch of the radial fork takes an oblique, sometimes almost perpen- 

 dicular direction to the lower branch, (like Meig, i. tab. vi. f. 7.) 



Gonomyia Meig. 



JJ. The second radial area has its usual elongated form, both branches of 

 the fork being more or less parallel. 



K. No petiolate areolet ; body black. Gnophomyia nob. 



KK. A petiolate areolet ; body yellow. Cladura nob. 



EE. Tibiae armed with spurs at the tip. 



L. Axillary vein very short, incurved to the anal angle ; wings like Meig. 

 i. tab. vii. f. 9 ; antennae long, (as long as head and thorax together) 

 setaceous, terminal joints indistinct. Trichccera Meig. 



LL. Axillary vein extending beyond the anal angle. 



M. Antennae from 6 to 10-jointed. 



N. No discal areolet ; wings like Meig. i. tab. vii. f. 8. Anisomera Meig. 



1859.] 



*The antennae are apparently 15-jointed in Elephantomyia nob. 



