1947] 
Banks — Characters in the Perlidce 
267 
Figures 1 to 8 I have indicated the gradual modification 
until it vanishes in Peltoperla. In Pteronarcys the anal 
brace extends obliquely backward (recurrent). Other 
general with an oblique recurrent anal brace are Acro- 
neuria , Togoperla, Banksiana, Neoperla, Perlesta, Ptero- 
narcella , Harrisiola, 2 Perlinella. 
In Iso genus the anal brace arises closer to the base of 
the anal cell and extends transversely to the margin; 
other genera in this group are Perlodes, Clioperla, Hy- 
droperla. Those in which the anal lobe is very small and 
folded under and the brace vestigial are Isoperla , Para- 
perla , Diploperla, some species placed in Clioperla (I am 
not sure of genotype). In Atoperla there is a very short 
basal part of anal brace arising before base of anal cell, 
often difficult to determine. In many cases the outer part 
of anal brace is weaker than basal part. In some species 
of Isoperla the lobe and brace are very small and weak 
or absent, in few distinct. In five genera the lobe and 
anal brace are absent: Peltoperla, Alloperla, Chloroperla, 
Kathroperla, and Hastaperla. In Perlesta , and some- 
times other forms, the anal brace is bent at the line of 
fold. 
Antennae. 
The antennae in Perlidae are rarely mentioned except to 
note the color. Walker, in the descriptions of two species 
( decolorata and decisa) says antennae “very minutely 
pubescent” and “brown, minutely pubescent.” 
The antennae of Pteronarcys and Acroneuria have 
joints near the base very short and broad, some, at least 
immovable; in Togoperla immarginata it is similar. In 
Perlodes the joints near base are usually longer, but still 
broader than long; also in Iso genus and Hydroperla. In 
many of the species placed by Needham and Claassen in 
Perla and Clioperla the third joint is plainly longer than 
the fourth, the latter and several following joints being 
much broader than long. In this type of antennae the 
joints are not narrowed at base until much further out 
2 Harrisiola (type Perla flavescens Walsh). I use this name for the spe- 
cies (except type) that were put by Klapalek in Neophasganophora ; the 
type species being a Perla. 
