108 THOMAS SAY FOUNDATION 



14. Pronotum usually with a median ill denned dark 



stripe; ninth abdominal tergite with a sugges- 

 tion of a tubercle ; supra-anal process very- 

 broad at base (side view) and with a slender 



upturned process at the tip mediana 



Entire insect usually pale yellowish or greenish 

 (except lineosa, which sometimes shows a nar- 

 row dark line on pronotum) supra-anal process 

 either slender or very small 15 



15. Abdomen with a dorsal dark stripe (in lineosa us- 



ually also a narrow dark line on pronotum) ; 



western species 16 



Entire specimen pale yellowish, without dark 

 dorsal line on abdomen 17 



16. Pronotum usually with a narrow dark line ; eight 



to nine mm. long; supra-anal process very 



short, with a small chitinized knob at the tip 



_ _„ lineosa 



Pale yellowish; eleven to fourteen mm. long; 

 supra-anal process, when extended, quite long 

 and consisting of a chitinized process sur- 

 rounded by a membrane, rounded at the tip 



pilosa 



17. Supra-anal process, raised, ending in a rounded 



knob with a serrate anterior margin ; western 



species serrata 



Supra-anal process not ending in a rounded knob, 

 and usually not with a serrate anterior margin ; 

 eastern species 18 



18. Supra-anal process very slender, finger-like, grad- 



ually tapering to a point imbecilla 



Supra-anal process more or less flattened, never 

 finger-like nanina 



Alloperla pallidula Banks. 



(Plate 22, figs. 12. 13.) 



1904. Chloroperla pallidula Banks, Trans. Ainer. Ent. Soc, 30:99. 

 ]907. Alloperla pallidula Banks, Cat. Neurop., p. 13. 

 1918. Alloperla inflrma Banks, Bull. Mus. Comp. Zool., Cambridge, 

 Mass., 62. No. 1:6. 



Length to tip of wings, male, 7-9 mm.; expanse, male, 

 13-16 mm. ; length to tip of wings, female, 8-10 mm. ; ex- 

 panse, female, 15-19 mm. 



General color pale greenish yellow with lateral margins 

 of prothorax blackish. Head hardly wider than pro- 

 thorax ; pale yellow with a little black around the ocelli, 

 hind ocelli a little closer to the eyes than to each other. 



