296 Ittinoris NaturAL History SurvEY BULLETIN 
Mature specimens with body length of 
approximately 21 mm. 
Nymphal and exuvial records: Near BALD- 
WIN, Pere Marquette River, Mich., May 9-10, 
1940, T. H. Frison & H. H. Ross, 17 exuviae ; 
1 nymph ready to produce adult, in poor con- 
NYMPHAL MANDIBLES 
ie 
a et 
SSEA va 
\ 
U 
NyYMPHAL 
MAXILLA 
SUPRA-ANAL 
PROCESS 
PLATE 
Ue 
ADULT HEAD 
AND PRONOTUM 
5 . 
eon 
~~ ae 
a 
G' GENITAL STRUCTURES 
Afi 
PL EE Ha i Hh 
Q SUBGENITAL PLATE 
G'ABDOMINAL TERGITES 
\\\ 
SUPRA-ANAL 
PROCESS 
SABDOMINAL SEGMENTS 
Fig. 66.—Hydroperla dorata. 
STRUCTURES 
Vol. 22, Artz 
Fig. 67——Nymph of Hydroperla dorata. 
dition, taken in spider web, otherwise with 
same data as for exuviae. 
This species differs from subvarians 
(Banks) and nalata Frison by having lat- 
eral stylets (paragenital plates). It differs 
from varians (Walsh), crosbyi (Need- 
ham & Claassen), parallela Frison and 
harti Frison in the shape of the supra-anal 
process and lobes formed by cleft tenth 
abdominal tergite. he nymph has a color 
pattern distinct from that of the nymphs 
of crosbyi and harti as illustrated by me 
(19352), and from that of varians as 
illustrated by me (1937). 
Hydroperla olivacea (Walker) | 
Perla olivacea Walker (1852, p. 144). Orig- 
inal description, ¢. 
Perla olivacea Ricker (1938, p. 142). De- 
scription of 9. 
