PLECOPTEKA OF NORTH AMERICA 137 



CLIOPERLA, new genus. 



Stoneflies of moderate or small size, having a yellow 

 dorsal stripe upon the prothorax, yellowish areas around 

 the eyes and rear of the head. The genital hooks of the 

 male when developed originate from the subanal lobes 

 and are less slender than in Isoperla. Ventral lobe on 

 male abdomen when developed is present on segment 8. 

 The radial sector forks far beyond the cord and in the 

 hind wing there are a few intercubital crossveins. The 

 cubito-anal crossvein of the fore wing is close to the apex 

 of the anal cell. 



Genotype, Isogenus clio Newman. 



Key to the Species. 



Males. 



1. No ventral lobe on abdominal segment 8 ebria 



Ventral lobe present 2 



2. Ventral lobe very weakly developed gravitans 



Ventral lobe well developed, conspicuous 3 



3. Subanal lobes developed as genital hooks similis 



Subanal lobes not developed as genital hooks__c//o 



Unknown are sobria, slossonae, annecta and mar- 

 morata. 



Females. 



1. Subgenital plate with a deep median cleft— sobria 

 Subgenital plate with hind margin entire 2 



2. Subgenital plate produced posteriorly well across 



the 9th sternite 3 



Subgenital plate scarcely prolonged posteriorly- _ 5 



3. Area of ocellar triangle black — eastern 4 



Area of ocellar triangle with a median yellow spot 



— western ebria 



4. Subgenital plate very broadly produced and even- 



ly rounded slossonae 



Subgenital plate truncate, not evenly rounded 



si mil is 



5. Wing membrane tinted with brown marmorata 



Wing membrane subhyaline 5 



6. Vein Rs 2-branched ; in hind wing the fusion of 



Rs and M extends more than half the length 



of the disc annecta 



Vein Rs 3-branched ; in the hind wing the fusion 

 of Rs and M is much less than half the length 



of the disc clio 



Unknown, C. gravitans sp. nov. 



