332 
already stated, I feel that until the true 
identity of clio is definitely established 
the name clio should not be used. My 
\ mehr 
Fig. 109 —Nymph of Jsoperla bilineata, 
dark phase. 
1935a listing of certain nymphs from Illi- 
nois as clio followed Claassen, and there- 
fore these records should now be associated 
with the name marlynia. 
As an aid to the recognition of mar- 
lynia, | am presenting new illustrations, 
fig. 108, of the adults secured by the rear- 
ing of nymphs, and also illustrations of 
the mouthparts of nymphs, fig. 108, and 
total dorsal views of three nymphs, frontis- 
piece. 
The three nymphs exhibit variations in 
color patterns displayed by nymphs col- 
lected at the same time and place and 
which, based upon reared adult material, 
Ittinots NATURAL History SURVEY BULLETIN 
Vol. 22, Artima 
are unquestionably of the same _ species. 
These nymphs should serve as a warning 
in placing too great reliance on color pat- 
terns alone when making specific deter- 
minations of Isoperla nymphs. ‘The gen- 
eral color patterns in this genus are a good 
guide to species, but consideration must 
be given to variation in the extension or 
diminishment of markings. “The light 
nymphal form of bilineata (Say) was 
figured in my 1935a paper, and this seems 
an opportune time to present an illustra- 
tion of a dark phase of the same species, 
fiz. 109. 
Isoperla marlynia has not been recorded 
since its original description. In addition to 
the records previously listed under clio which 
should be associated with this name, and 
which are specifically mentioned in a_pre- 
ceding paragraph, I can now add the follow- 
ing records. 
ILLINOIs.—RocKFoRD, Rock River: April 3, 
1928, Frison & Ross, 1¢ nymph. Rock IsLANnp, 
Rock River: April 2, 1928, Frison & Ross, 
19 nymph; April 27, 1932, Frison & Mohr, 
1 exuvia. (Listed by Frison 1935a as clio.) 
INDIANA.—RocErRS, White River: March 14, 
1936, Frison & Ross, 7 nymphs; April 16, 
1936, Ross & Mohr, 1 exuvia; April 19, 1936, 
Ross & Mohr, 192 with exuvia (reared) ; 
April 24, 1936, Frison & Mohr, 19; April, 
1940, Mohr & Burks, 1 exuvia; April 10, 1940, 
Mohr & Burks, 1 nymph, 2Q with exuviae 
(reared) ; April 20, 1940, Mohr & Burks, 1¢ 
with exuvia (reared); April 21, 1940, Mohr 
& Burks, 1¢ (reared). 
MANITOBA.—CHURCHILL: July 23, 1936, H. 
E. McClure (19CH73), 1¢@. 
MICHIGAN. — NAHMA JUNCTION, Sturgeon 
River: May 12, 1940, Frison & Ross, 9 
nymphs; same except May 14, 26 and 2 
with exuviae (reared) ; same except May 15, 
7a and 9Q with exuviae (reared); same 
except May 16, 16 and 19 with exuviae 
(reared) ; same except May 17, 49 with exu- 
viae, 14 (reared) ; same except May 20, 2¢ 
and 49 with exuviae (reared). Ontonagon 
County, between SirveR CiTy and ONTONAGON, 
shore of Lake Superior: May 15, 1935, J. W. 
Leonard, 19. Rapm River: May 12, 1940, 
Frison & Ross, 1 nymph. 
VIRGINIA.—REMINGTON, Rappahannock Riv- 
er: March 21, 1940, Frison, Mohr & Hawkins, 
3 nymphs; same except April 2, 22 with 
exuviae (reared); same except April 3, 19 
(reared). 
WISCONSIN.—EDGERTON: June 5, 1936, Frison 
& Ross, 12. 
Isoperla burksi new species 
Mate. — General body color yellow 
with brown to fuscous markings. Dor- 
sum of head with dark brown V-shaped 
area connecting ocelli and then extending 
forward to tip of head, fig. 110. Pro- 
