PLECOPTERA NYMPHS OF NORTH AMERICA = 83 
Legs broad and much flattened; femora covered with fine 
hairs, interspersed with stout spines; along their middle a nar- 
row, longitudinal line, in which the hairs are absent; the entire 
leg bears a thick fringe of long hairs on the outer margin. 
Abdomen somewhat flattened and usually uniformly brown 
or blackish in color, although in some of the lighter specimens 
there is a tendency for a yellowish spot to appear on the posterior 
half of each segment along the median dorsal line; the abdominal 
segments are all bordered posteriorly with a fringe of short 
spines; on the tenth tergite these are a little longer. Cerei very 
long and on the inside with a thick, wide fringe of long hairs, 
especially copious at the base, gradually becoming shorter and 
thinner toward the tip, and extending the entire length of the 
cerci; the individual segments, of which there are about sixty, 
each bearing a whorl of spines on the posterior margin. 
Hight pairs of branched, tracheal gills as follows: two pairs 
at the outer base of the prothoracie legs; one pair each on the 
outer conjunctivae between the pro- and mesothorax, and between 
the meso- and metathorax; two pairs at the outer base of the 
mesothoracic legs; one pair at the outer base of the metathoracic 
legs, and one double pair at the caudal base of the metathoracie 
legs; anal gills absent. | 
Mouth parts. Labrum about three times as wide as long; black- 
ish, the front margin having a fringe of long hairs. Mandibles 
somewhat asymmetrical, each with five distinct, sharp teeth, of 
which the first, second, and fourth are the largest; following 
these teeth is a fringe of long, stout hairs. Maxillae with laeinia 
bidentate, with a series of long, stout hairs; galea distinctly two- 
seomented, cylindrical, slender, shorter than the lacinia, and with 
a small bunch of hairs at the apex; maxillary palpus five-segment- 
ed, first about as long as wide, second a little more than twice as 
long as wide, the apical segment only about half as long as the 
fourth, and much more slender. Labium very broad; submentum 
much broader than long; glossae short, more or less triangular ; 
paraglossae large with long hairs on the inner margin; the three- 
segmented labial palpus extends beyond the paraglossae; the 
first segment about twice, or a little more than twice, as long as 
wide ; second about a third again as long as first, the third about 
two-thirds as long as the second, and much more slender. Hypo- 
pharynx rounded and normally extending nearly to the tip of 
the glossae. ; 
This species is common in the larger swift-water streams of 
the Eastern States. The long thick fringes on the legs and the 
