PLECOPTERA NYMPHS OF NORTH AMERICA 95 
Mouth parts. Labrum nearly half again as wide as long; an- 
terior margin nearly straight and with a fringe of short hairs. 
Mandibles with four or five unequal teeth followed by a well- 
developed molar which is fringed with a comb of short, closely 
set, blunt hairs; beyond the comb is a bunch of longer hairs. 
Maxillae stout; lacinia terminating in two or three denticles, 
followed by a fringe of hairs; galea cylindric, extending a little 
beyond the tip of lacinia and at the tip with a few hairs; maxil- 
lary palpus stout and extending far beyond the tip of the lacinia. 
Labium : mentum very narrow; submentum large, subquadrangu- 
lar; glossae and paraglossae about equally long but the para- 
glossae much wider than the glossae; at the tip the glossae and 
paraglossae bear small papillae; labial palpi very stout and not 
extending much beyond the tip of the paraglossae; third seg- 
ment of labial palpus very large. | 
In general appearance these nymphs are of a dirty brown 
color, due to the adherence of small particles of organic matter. 
The spiny legs and the fringe of short stout spines around the 
margin of the pronotum as well as at the anterior angles of the 
meso- and metanotum are characteristic of Nemoura. 
The nymphs occur largely in small upland streams where they 
may be found in the leaf drift. 
Ithaca, N.Y. 
Nemoutea vallicularia Wu 
Length of body up to 7 mm.; antennae up to 4 mm.; cerei up 
to 4 mm. 
In general appearance very similar to NV. sinwata. The nymphs, 
however, have no gills in the cervical region. Wu (57) who has 
studied the morphology and biology of this species found that it 
passes through twenty-two instars and completes its life cycle in 
one year. 
Ithaca, N.Y. 
Nemoura venosa Banks 
(Plate 9, figs. 141-146.) 
Length of body up to 6.5 mm.; antennae up to 3.8 mm.; cerci 
up to 3.7 mm. 
General color yellowish brown to darker brown. Very similar 
in appearance to N. sinuata but differs as follows: the gills in 
the cervical region are in four groups, each group made up of six 
to seven finger-like gills. The fringe of hairs around the margin of 
the pronotum and on the antero-lateral angles of the meso- and _ 
