ISOPTERYX. 31 



39. P. citrinella. 



Perla citrinella Newp. Proc. Linn. Soc. I, 388, 6. Newp. Trans. Linn. 

 Soc. XX, 540, 1. P. citrinella Walk. Catal. 169, 97. 



Pale luteous ; the head as wide as the prothorax, ocelli fuscous ; 

 antennae fuscous, pale at base ; prothorax not broader behind, 

 luteous, subrugulose, the anterior margin and middle line blackish, 

 angles obtuse, sides incurved ; wings hyaline, veins pale. (From 

 the description of Mr. Walker.) 



Length to tip of wings(?) 13 millim. Alar expanse 23 millim. 



Hub. St. Martin's Falls, Albany River, Hudson's Bay (Barn- 

 ston) ; Nova Scotia (Redman.) 



Unknown to me. The description of Mr. Newport differs a 

 little : " antennae entirely black." The description of Mr. Walker 

 was drawn from the typical specimen. Is it an Isopteryx? 



40. P. imbecilla. 



Sialis imbecilla Say, Godman's West. Quart. Rept. II, 165, 3. 



Pale green, immaculate ; head with three fuscous ocelli, antennae 

 rather obscurer, pilose ; prothorax transversely oval, rugulose ; 

 wings greenish-white. (Taken from the description of Mr. Say.) 



Length to tip of wings 9 millim. Alar expanse 16 millim. 



Hub. Ohio River at Cincinnati. Common in the middle of 

 May (Say). Unknown to me. Is it an Isopteryx? 



ISOPTERYX Pict. 

 Wings with the transverse veins rare, almost absent ; no basal 

 space to the posterior wings ; palpi setaceous, last articulation 

 shortest. 



1. I. cydippe ! 



Chloroperla cydippe Newm. Mag. Nat. Hist. ser. 2, III, 88, 8. Pict. Perl. 

 317. Walk. Catal. 1G8, 88.— Chi. sulphur ea Fitch! (Collection of 

 de Selys Longchamps.) 



Pale yellow, immaculate; head hardly broader than the pro- 

 thorax, three black ocelli ; antennae nigro-fuscous, base pallid : 

 prothorax transversely oval, subrugulose, angles rounded ; feet 

 pale, tarsi nigro-fuscous; wings greenish-hyaline, veins pale. 



Length to tip of wings £ t ? 9 millim. Alar expanse J" 13 

 9 16 millim. 



