34 THOMAS SAY FOUNDATION 
Pteronarcys sp. 
I have before me a unique Pteronarecys nymph which was col- 
lected from the Boquet River, Elizabethtown, New York, July 
20, 1929 by Mr. Sid Robinson. This nymph is not fully grown, 
and measures only 16 mm. in body length. It.is most closely re- 
lated to Pt. biloba, but differs from biloba in several respects. 
The color is almost black, with a yellow, transverse elongate spot 
on each side of the posterior margin of the pro-, meso-, and meta- 
notum. Antennae blackish, with a yellow band in the middle, and 
yellow at the tips. Cercei also with a middle yellow band. At the 
base of the mesothoracic wing pad there is a sharp lateral spine, 
and the wing pads are sharply pointed. Abdominal segments one 
to seven with large lateral hooks, and just a suggestion of a hook 
each side of the eighth segment. 
The spine at the base of the mesothoracic wing pads, the colora- 
tion, and the absence of hooks on the eighth abdominal segment 
preclude this from biloba. It may possibly prove to be Pt. com- 
stockt Smith. 
Genus PTERONARCELLA Banks 
This genus is very closely allied to Pteronarcys, but the 
nymphs, when fully grown, are much smaller (not over one inch 
in length), and are readily distinguished from Pteronarcys by 
the fact that, in addition to having tufted gills on the first two 
abdominal segments as in Pteronareys, they also have tufted 
gills on the third abdominal segment. The genus occurs only in 
the Western States. 
Color nearly uniform brown, mostly with inconspicuous lighter 
markings, and sometimes with light longitudinal lines on the 
abdomen. 
Head much narrower than prothorax; brown, sometimes with 
a blacker area over the ocellar triangle, and with a rounded light 
spot on either side of the ocellar triangle; three small ocelli ar- 
ranged in an equilateral triangle; antennae about as long as 
pro-, meso-, and metathorax together, composed of fifty or more 
seoments in the mature nymph; antennal plates narrow and low. 
Mouth parts of the herbivorous type, very similar to those of 
Pteronarcys. 
Pronotum much wider than long with broadly rounded angles, 
and with the lateral margin flaring out considerably ; dises brown 
and somewhat rugulose, the lateral margins smooth and lighter 
in color. Meso- and metanotum brown; wing pads large in mature 
nymphs, and extending out far from the body. Legs quite stout ; 
