100 THOMAS SAY FOUNDATION 
Leuctra claasseni Frison 
The following description is taken from Frison (6). 
Nymphal Male. General color yellow-brown, general body form 
elongate; about 8 mm. long. 
Head much wider than prothorax, widest at compound eyes, 
rounded behind; epicranial stem about as long as one-half of 
width of prothorax; developing ocelli in same relative positions 
as in adult; labrum somewhat perpendicular to plane of front. 
Antennae long and slender, fifty or more segments in each an- 
tennae; first segment very large, basal segments wider than long, 
succeeding segments gradually becoming more elongate and with 
apical segments several times as long as wide, a few setae on 
segments. 
Labium with glossa divided into two parts by an incision which 
extends longitudinally as a suture less than one-half the length 
of the ligula; paraglossae about as broad as glossae combined, 
and not extending beyond them; palpiger distinct and almost 
appearing as short basal segment of palpus; labial palpus three- 
segmented, basal segment shortest, second and third segments 
longer than first, and of about equal length, third or terminal, 
segment less broad than second, and gradually rounded and taper- 
ing at apex. Hypopharynx about as large as leula, lobe-like, 
rounded at apex, and not extending beyond glossae. Maxillae 
well developed; lacinia with two slender, sharp teeth curved in- 
wards at apex, beneath which on inner side is a row of long stiff 
setae; galea extending slightly beyond lacinia, curved and taper- 
ing to a point at apex; palpifer indistinct, and appearing as basal 
segment of palpus, maxillary palpi five-segmented and about 
twice as long as labial palpi, basal or first segment very short and 
likely to be confused with palpifer, second segment shortest and 
about one-half as long as fifth, third and fourth segments sub- 
equal, fifth segment a little longer than third. Mandibles heavily 
chitinized, with several teeth directed inwardly near apex, be- 
neath which on inner margin is a well-developed molar with short 
stiff setae. 
Pronotum with darkly chitinized area almost quadrate, with 
front angles slightly rounded and hind angles conspicuously so. 
Meso- and metathorax supporting wing pads which extend back- 
wards nearly parallel with body. Fore wing pads long and nar- 
row, overlapping basal third of hind wing pads. Hind wing pads 
likewise, long and narrow, with anal lobe not extending much 
beyond middle of wing pad; venation of wing pad, when dis- 
