298 
Labium, maxillae and mandibles as in 
fig. 68. 
Dorsum of abdomen terminating in a 
coiled tubular projection not heretofore 
Fig. 69.—Nymph of Hydroperla olivacea. 
observed in any other described stonefly 
nymph, fig. 69. 
No thoracic or anal gills; submental 
gills present as in all Hydroperla. 
Approximate body length of mature 
nymph 15 mm. 
Records of this species are as follows. 
MICHIGAN.—BALDWIN, Pere Marquette Riv- 
er: May 28, 1939, 4 exuviae, and May 9-10, 
1940, 19 exuviae, 1 nymph, 1¢ adultes baht 
Frison & H. H. Ross. Honor, Platte River: 
May 27, 1939, 14 exuviae, and May 10, 1940, 
22 exuviae, 1 partially emerged adult, eet? 
Frison & H. H. Ross. Nirvana, Sanborn Creek: 
May 28, 1939, T. H. Frison & H. H. Ross, 5 
exuviae. PEAcocK, Little Manistee River: May 
ItLinois Natura History SuRVEY BULLETIN 
Vol. 22, Aree 
10, 1940, T. H. Frison & H. H. Ross, 10 exu- 
viae. NAHMA JUNCTION, Sturgeon River: May 
12, 1940, 8 exuviae, 14 adult, T. H. Frison 
& H. H. Ross. Lake County, Pine River 
Station 4: May 16, 1938, O. H. Clark, 16 
adult. 
WISscoNsIN. — SPOONER, Namakagon River: 
June 5-6, 1936, T. H. Frison & H. H. Ross, 
Powexuvia: 
Hydroperla parallela Frison 
Hydroperla parallela Frison (1936, p. 261). 
Original description, ¢. 
Hydroperla parallela 
Description, @. 
parallela Ricker (1939, p. 238 
Frison. (1937, p. 90). 
ene 
Additional British Columbia records. 
Since my original description of the 
male (1936), and subsequent description 
of the female (1937), I have examined 
nymphal specimens which I am certain 
are parallela, and the following descrip- 
tion is presented. 
Fig. 70—Nymph of Hydroperla parallela. 
