NATURAL SCIENCES OF PHILADELPHIA. 233 



Thorax ochraceous, yellow or brown, 11 



9. Thorax with four distinct brown stripes, the intermediate ones approxi- 



mated ; antennae and feet fuscous ; wings hyaline, stigma pale ; the third, 



fourth, fifth and sixth joints of the antenna? almost coalescent ; long. lin. 



2f 3. (Section 6th,) L. ultima nob. 



Stripes of the thorax indistinct, 10 



10. Petiolate areolet unusually short, almost rudimental ; wings hyaline, 

 slightly subcinereous ; stigma pale ; body brown, thorax subcinereous ; 

 long. lin. 2f, (Section 5th,) L. brevifurca nob. 



Petiolate areolet longer or not much shorter than the petiole ; body dark 

 cinereous ; wings yellowish or infuscated ; stigma fuscous ; base of 

 femora ferruginous; long. lin. 4 5. (Section 8th. Prion olabis nob.) 



L. rufibasls nob. 



11. Mediastinal cross-vein close by the tip of the mediastinal vein ; the discal 

 areolet has the usual proportions, 12 



Mediastinal cross-vein removed from the tip of the mediastinal veins at a 

 distance about equal to the length of the great cross-vein ; discal areolet 

 elongated, about twice as long as in the other species of the genus ; body 

 pale yellow ; wings hyaline, stigma pale ; long. lin. 2| 3|, (Section 

 5th,) L. areolata nob. 



12. Thorax shining, 13 

 Thorax not shining, body brownish yellow ; wings hyaline, with a pale 



stigma, 14 



13. Body and feet yellowish ferruginous ; wings slightly infuscated at tip ; 

 stigma pale fuscous ; stigmatical cross-vein beyond the origin of the radial 

 fork; long. lin. 3 4, (Section 5th,) L. adusta nob. 



Body brown, pleurae yellow ; wings infuscated ; stigmatical cross-vein close 

 by the origin of the radial fork ; antenna? of the <$ longer than head and 

 thorax together; long. lin. 3 4, (Section 4th,) L. tenuipes Say. 



14. The petiole forms an almost straight line with the radial vein ; long. lin. 

 3] 4, (Section 5th,) L. imbecilla nob. 



The petiole forms an almost straight line with the cubital vein ; radial vein 

 conspicuously arcuated before its forking ; long. lin. 3 3^, (Section 5th,) 



L. toxoneura nob. 



15. Wings pubescent on the whole surface; body brown ; long. lin. 3^, (Sec- 

 tion 12th,) L. pilosella nob. 



Wings not pubescent, 16 



16. Cinereous, with pale ferruginous feet and brown tips of femora, tibia? and 

 tarsi; long. lin. 2| Z\, (Section 11th,) L. quadrata nob. 



Pale yellow, stigma pale ; long. lin. 2| 2\. (Section 11th,) L. lenta nob. 



1st Section. 



(Subgenus Lasiomastix nob.) 



Antenna? of the <$ as long or a little longer than the body, slender, filiform ; 

 two basal joints short, the following elongated, cylindrical, of nearly equal 

 length, clothed with soft, erect hairs ; the third and fourth joints have a small 

 spine on the underside, at the tip; antenna? of the 9 setaceous, not reaching 

 much beyond the base of the wing ; joints cylindrical, clothed with sparse hairs.* 

 Palpi a little longer than the head; last joint longer than the preceding. Wings 

 somewhat like Meig. i. tab. vi. f. 3. Forceps of the male like the typical 

 Limnophila?; upper horny falciform appendage slender and jointed ; lower 

 one short, stout, with the point turned upwards. 



* It is difficult to count the number of joints of the ^ antenna?, even in fresh speci- 

 mens, although in judging from analogy, it is extremely probable that there are 16. One 

 of the has apparently but 15 joints. 



1859.] 



