THE CANADIAN ENTOMOLOGIST. 221 



NOTES ON THE CLASSIFICATION OF THE PERLID^. 



BY NATHAN BANKS, EAST FALLS CHURCH, VA. 



In a recent paper on the genus C/ihroperla I divided this genus, as 

 it had been used, into two genera; neither of which being a true 

 Chloroperla^ I proposed the names Tsoperla and Ailoperla. The charac- 

 ter I used in this division was one proposed by Prof. Needham to separate 

 the Perli?ii from the Ne7)iourini. This is the condition of the median 

 vein near the base of fore wings, whether united to the radius, or running 

 parallel to the radius. In Isoperla the median vein is as in Per/a, running 

 parallel to the radius ; while in AHoperla the median vein is like the 

 JVemourini, united at an angle to the radius. From a study of the anal 

 region of the fore wings I find that these two genera can be more readily 

 known by another character, and that in this respect also Alioperla is 

 related to the Ne7notcri7ii. This new character is the condition of the 

 two lower branches or veins from the anal cell ; in Isoperla (type C. 

 bilineata, Say), these two veins arise separately, as in Ferla, but in 

 Alioperla (type C. it?ibedlla, Say), these two veins unite before the cell, 

 or rather, there is one forked vein instead of the two simple ones. This 

 latter condition obtains in the Nemouri7ii. The application of this 

 character places the same species in Isoperla and Alioperla as does the 

 condition of the median vein. 



In the Ne77i07iri7ii there is one forked vein from the lower part of the 

 anal cell, the outer branch bowed up to form an elongate cell. In the 

 Cap7ii7ii there is but one vein from the anal cell below, and this is not 

 forked, a character which will distinguish this tribe from other Perlidce. 

 In the Trans. Amer. Ent. Soc, XXVI, p. 240, 1900, I separated the 

 Cap7ii/ii by the unbranched radial sector ; there are, however, one or two 

 exceptions, or rather, the apical venation is confused so that the radial 

 sector appears branched ; the character of the anal region seems to be 

 constant, and the two characters together will readily distinguish this tribe. 



T\\Q Ptero7iarci7ii di^tr {vova all other Perlidce. m. having a series of 

 cross-veins in the anal region ; as well as by their approximate anterior 

 coxae. 



In the true Perlini there are two simple branches from the anal cell 

 below ; but in two species of Acro7ietiria (pacifica and tiigrita) there are 

 three branches, or one simple and one forked vein ; in some other species 

 of Acro7teuria one of the branches is sometimes forked. 



Several authors have divided the PerlidcB into two sub-families, 

 Perli7icB and Ne77iotiri7ice, but the structure of Alioperla, related to Perla 



July, 1906 



