14. 
16. 
Lifes 
1 Perr 
19. 
PLECOPTERA NYMPHS OF NORTH AMERICA 25 
Maxillae very large and projecting out laterally from the 
head so as to be plainly visible from above; i.e. the elbows 
of the eardo and stipes stand out so as to increase the ap- 
parent diameter of the head. Gill-less Perla and Isogenus 
no cas ROR eR ee Oo (p. 46 and 45) 
Maxillae not unusually large and not plainly visible from 
VOU RD 3 Bug NR re RSS oP Ae eta ee i ce oe 15 
. Apical segments of maxillary and labial palpi slender and 
drawn to a sharp point; lacinia almost equally wide up 
to the base of the teeth; not brightly colored nymphs, 
without longitudinal stripes on the abdomen.......... 
RP ie ce RYU te oe, Ai gs Clioperla (p. 68) 
Apical segments of palpi not very slender and not drawn to a 
sharp point; lacinia gradually narrowing to the base of 
the teeth; mostly contrastingly colored nymphs with 
longitudinal stripes on the abdomen...... Tsoperla (p. 71) 
Hind wing pads diverging considerably outward from the 
body (except in Leuctra where the wing cases are long 
and narrow, the hind ones about as narrow as the front 
ones and lying parallel with the body, and the labial palpi 
extending far beyond the tip of the ligula); gills, when 
present, either at the throat or as single filaments at the 
amor be Gn CUS sae rete ects cae) ed Fs NEMOURIDAE 17 (p. 92) 
Hind wing pads not much divergent from the body and wider 
than the front ones; gills absent; labial palpi never reach- 
ing beyond the tip of the ligula...... CAPNIIDAE 19 (p. 109) 
First and second tarsal segments subequal in length; hind 
wing pads very wide and diverging almost at right angles 
from the body, i.e. the anal margin; gills, if present, 
3-seemented single filaments attached to coxae ........... 
5 Se ae eee ee Taenmopteryx (p. 101) 
First segment of tarsus much longer than second; gills, when 
fenecent el OGaredent-the.toroatr: «ac gam ska cr. ale eres 18 
Body stocky and hairy; usually a fringe of hairs around 
margin of pronotum; hind wing pads much wider than 
front ones; gills, if present, at throat; labial palpi not 
ERLE INCAS VOM MIG UI Awlsce: ces capese\eees ot: Nemoura (p. 92) 
Body slender, smooth; hind wing pads hardly wider than 
front ones; no gills; labial palpi extend beyond ligula 
2 er EES ER cel Se eee Leuctra (p. 96) 
Anal field of hind wing pad extends far beyond middle of 
GURL YOO Rik og ea a ea ere Allocapnia (p. 111) 
Anal field of hind wing pad does not extend much beyond 
the middie of the wing case............. Capnia (p. 109) 
