PLECOPTERA NYMPHS OF NORTH AMERICA © 31 
General color chocolate brown to dark brown, paler on the 
ventral surface. 
Head much narrower than pronotum; brown, with rounded, 
smooth, yellowish dises on each side of the ocellar triangle; an- 
tennal plates prominent but not much produced; occiput with © 
many longitudinal rugosities. Antennae brown, the middle third 
usually paler, composed of sixty to sixty-five segments. 
Pronotum nearly twice as broad as long, slightly widened 
posteriorly, the angles all somewhat produced, but less than in — 
biloba; front margin a little arcuate, hind margin convex; discs 
rugose. 
Legs brown, femur, tibia, and tarsus fringed with long hairs. 
Abdomen brown, segments one to seven with lateral apical 
hooks, and usually also a suggestion of a hook on segment eight. 
These hooks are directed backwards and lie close to the body ; 
tenth tergite much produced. Cerei brown, usually a lighter band 
in the middle, and lighter at the tip; thirty to thirty-five seg- 
ments. 
The chief difference between proteus and biloba is the structure 
of the abdominal hooks, the length of cerci and the shape of 
the pronotum; biloba always has distinct hooks on segment eight 
and all hooks are directed away from the body, proteus has only 
a suggestion of hooks on abdominal segment eight, and even on 
seven the hooks are often inconspicuous, while the remainder of 
the hooks are always close to the body. The cerci are shorter in 
proteus than in biloba; the front angles of: the pronotum are 
less produced in proteus than in biloba. The gills are very simi- 
lar to those of biloba. 
A juvenile specimen, 10 mm. long has only ten pairs of gills 
which are distributed as follows: three pairs in the cervical 
region, two pairs between pro- and mesothoracic legs, two pairs 
between meso- and metathoraciec legs, one pair between the hind 
pair of legs, and one pair on each of the first abdominal segments. 
From Ithaca, N.Y.; Danby, N.Y.; Boquet R., Elizabethtown, 
N.Y.; Wilmington, N.Y.; Lake George, N.Y.; Blossburg, Pa. 
Pteronarcys dorsata Say 
(Plate 1, figs. 1-5; plate 11, figs. 173-174; plate 34, fig. 231.) 
Length of body up to 40 mm.; antennae up to 23 mm.; cerci 
up to 17 mm. 
Color dark brown, sometimes almost uniformly so, but in 
some specimens with lighter markings on thorax and abdomen. 
Head brown, with a lighter area on each side of the ocellar tri- 
