PLECOPTERA NYMPHS OF NORTH AMERICA 79 
Three alcoholic specimens from Fox River, Ottawa, Illinois, 
May 31, collected by W. A. Howard. 
Genus PERLINELLA Banks 
This genus, of which only one species, P. drymo Newman, is 
known from North America, is readily recognized by its almost 
uniformly yellowish brown color; its long head with small eyes 
set far forward on the head so as to be located on a line almost 
even with the front ocellus; its long, branched, copious gills 
on the thorax; and a pair of small caudal gills. The mature 
nymphs are medium sized, measuring less than an inch in length 
when fully grown. Antennae and cerci each almost half as long as 
the body; three ocelli, the anterior one small. 
Pronotum transversely oval; wing pads wide, rather broadly 
rounded on the sides and at the apex. Legs fringed with long 
hairs. First two segments of tarsus very short, the third one 
about four times as long as one and two combined. 
Abdomen slightly flattened; tenth tergite produced into a 
median rounded lobe; cerci long and slender with the apical seg- 
ments very long. 
Generally distributed east of the Mississippi River. 
Perlinella drymo Newman 
(Plate 8, figs. 117-122; plate 22, fig. 201; plate 32, fig. 225.) 
Length of body up to 22 mm.; antennae up to 10.5 mm.; cerci 
up to 12 mm. 
Yellowish brown. Readily recognized by its long head, small 
eyes set far forward, and by its much-branched, copious, long 
tracheal gills. Head almost as long as wide, slightly wider than 
pronotum; yellowish with an irregular transverse dark band, 
and with darker areas on the eclypeus and occiput; ocelli small, 
placed in an equilateral triangle; eyes small, set forward in the 
head so as to be nearly in line with the front ocellus; antennae 
yellow, long and slender. 
Pronotum transversely oval, about half again as wide as long, 
almost uniformly brownish, with a dark narrow marginal groove ; 
_ surface nearly smooth; sides and angles broadly rounded. Meso- 
and metanotum irregularly marked with brown and yellow; wing 
pads broadly rounded on the sides and with tips broadly rounded. 
Legs fringed with long hairs; first and second tarsal segments 
very short, subequal, the third about four times as long as one 
and two together. 
