PLECOPTERA NYMPHS OF NORTH AMERICA 29 
ment five nearly three times as long as wide. Palpi sparsely 
clothed with hairs. Galea rather broad and blunt, and slightly 
longer than the lacinia; made up of two segments, a short basal 
one about one-fourth the length of the entire galea, and larger 
distal one clothed with hairs, and at the tip a bunch of spinules. 
Lacinia bears three teeth at the tip, two of which are about equal 
in length, the third short ; inner surface grooved, and the ventral 
carina which borders the groove bears a row of long hairs. 
Labium and hypopharynx: labium almost twice as long as 
wide; glossae and paraglossae about equally long so that the 
labium is made up of four subequal lobes, the lobes hairy and 
bearing at their tips bunches of hairs or spinules, the glossae 
always bearing a bunch of hairs, and the paraglossae bearing 
either hairs or spinules. Mentum narrow and broadly triangular ; 
submentum a little wider than long and widened posteriorly with 
the posterior margin sinuate. Labial palpi with three segments, 
first a little longer than wide, second half again as long as wide, 
third almost twice as long as wide. Entire labium more or less 
clothed with hairs. 
Key to Nymphs of Pteronarcys 
1. Abdominal segments with large lateral teeth or hooks..... 2 
Abdominal segments without lateral hooks .............. 3 
2. Hooks on abdominal segments large and directed outward, 
those on segments seven and eight almost as large as the 
preceding ones; ceri more than half as long as abdomen; 
front angles of pronotum produced. .biloba Newm. (p. 30) 
Hooks appressed to body, small on segment seven, and in- 
conspicuous on eight; cerci less than half as fone as abdo- 
men; front angles not noticeably produced ............. 
co oh SE a ee a proteus Newm. (p. 30) 
3. Lateral prothoracie teeth long, slender, sharp, and directed 
outward; supra-antennal plate prolonged into a sharp 
tooth; wing pads pointed...... californica (Newpt. (p. 32) 
Lateral prothoracic teeth short and not directed outward so 
much; supra-antennal plate blunt; wing pads rounded.. 4 
4. Eastern species; prothoracie teeth usually as long as wide; 
ninth sternite of male produced beyond the tenth; tenth 
tergite of female nearly straight...... dorsata(Say)( p. 31) 
Western species; prothoracic teeth usually shorter than wide ; 
ninth sternite of male narrow and not produced; tenth 
tergite of female with the apex considerably elevated.... 
= 3 Mahe ee ee ere princeps Bks. (p. 33) 
