294 
of compound eye to lateral ocellus much 
shorter than distance between lateral 
ocelli. Submental gill remnant present. 
DOES 
RIGHT WINGS 
ORL fewer 
i) J PaARAGENITAL PLATES 
SupRA-ANAL AND 
Process SupRA-ANAL PROCESS 
& TERMINAL 
ABDOMINAL 
A ERGITES 
o TERMIN 
SEGMENTS 
cape 1 saul 
o HEAD AND 
PRONOTUM 
APEX OF 
o* ABDOMEN 
Fig. 63.—Hydroperla nalata. 
Ittinois NATURAL History SURVEY BULLETIN 
Vol. 22, Art 
Pronotum approximately quadrangular, 
broader than long, a distinct pattern of 
raised rugosities on surface each side of 
yellow, median longitudinal stripe, as 
shown in fig. 63. 
Wings with veins black or dark brown, 
and membranous interspaces hyaline; ven- 
ation as in fig. 63. 
Abdomen with tenth tergite cleft, the 
lobes formed by this cleft with sides ad- 
jacent to cleft almost parallel so that lobe 
is broad at base and not thumblike as in 
some species of the genus; supra-anal 
Fig. 64——Nymph of Hydroperla nalata. 
process tapering to a point which is some- 
what recurved backwards at tip, without 
lateral stylets (paragenital plates) flank- 
ing it, and enveloped by two lobes which 
are partly sclerotized, fig. 63; aedeagus as 
in fig. 63, 
