18 NETJROPTERA OF NORTH AMERICA. 



2. P. ruralis ! 



P. ruralis Hagen ! 



Testaceous ; bead broader than the prothorax, a curved fuscous 

 line in front ; antennae fusco-testaceous, the second articulation 

 and some of the following ones luteous ; the prothorax quadran- 

 gular, short, equal, rugulose, angles rather obtuse ; feet testaceous, 

 knees fuscous ; abdomen beneath yellowish, setae yellowish, behind 

 the base banded with fuscous, hardly pilose ; 9 antepenultimate 

 ventral segment a little rounded, produced, before the apex a linear 

 transverse tubercle ; wings sub-hyaline, the veins luteous ; anterior 

 wings with the subcostal accessory veinlet five-branched, transverse 

 veins very numerous. (Female.) 



Length to tip of wings 31 millim. Alar expanse 57 millim. 



Hob. St. Louis. 



3. P. arida! 



Perla arida Hagen ! 



Yellowish-fuscous ; head broader than the prothorax, yellowish, 

 clouded with fuscous anteriorly ; antennae fuscous, second articula- 

 tion yellowish ; prothorax narrower posteriorly, angles acute, sides 

 straight, rugulose, middle line yellowish ; the feet luteous, knees 

 fuscous ; the abdomen beneath luteous ; setae pilose, yellow, arti- 

 culations of the tip fuscous at their apex ; J" last ventral segment 

 large, ovate ; 9 antepenultimate ventral segment with a middle 

 lamina narrow at base and at the apex two-lobed ; wings sub- 

 hyaline, veins fuscous ; anterior wings with the subcostal accessory 

 vein three-branched, transverse ones few. 



Length to tip of wings 23 J", 28 9 millim. Alar expanse 

 43 $ , 53 9 millim. 



Hob. New York, Philadelphia. 



Is this not P. arenosa Pictet, tab. x, fig. 2, from Philadelphia? 



O O Submarginal space of the anterior wings not 

 charged with transverse veins. 



a. Subcostal accessory veinlet of the anterior wings with four 

 incurved branches. Subgenus Isogenus Newm. Nephelion Pict. 



4. P. frontalis ! 



Isogenus frontalis Newm.! Entom. Mag. V, 178. Mag. Nat. Hist. Ill, 25. — 

 Nephelion frontalis Pict. Perl. 172, 8 ; tab. viii, fig. 10—11. Walk.! 

 Catal. 144, 10. — Perla bicaudata Kirby, Fn. Bor. Am. 252. 



