292 Ittinotis NATURAL History SURVEY BULLETIN 
this and other characters are closely re- 
lated to Perlodes and Hydroperla. 
To aid with the future identification of 
adults of frontalis, I wish to present the 
illustrations in fig. 59 made from speci- 
mens reared from nymphs in northern 
Michigan: head and pronotum; seventh 
abdominal sternite of male; dorsal and 
lateral views of terminal abdominal seg- 
ments of male; three views of supra-anal 
process, lateral stylets and enveloping 
lobes; and the subgenital plate of the 
female. 
Claassen (1931) does not describe the 
nymph of frontalis but questionably de- 
scribes a nymph without locality label 
as “colubrinus (?).” His determination 
was based upon the fact that the nymph 
was a mature female about to produce the 
adult, and certain adult structures were 
visible. As I stated above, I consider colu- 
brinus a synonym of frontalis. No illustra- 
tion is given by Claassen of the dorsal 
view of the nymph, but the mouthparts 
are figured and agree in general with the 
mandibles, maxilla and labium, fig. 59, of 
a nymph, fig. 60, whose association with 
frontalis has been established by rearings. 
Claassen (1931) failed to note the sub- 
mental gills, fig. 59, in his verbal descrip- 
tion and drawing of the labium, but they 
are present and are a key, among other 
characters, to the close relationship of this 
genus with Hydroperla and Perlodes. 
Records of frontalis in the Illinois Natural 
History Survey collection and of specimens 
determined for others are as follows. 
ALBERTA.—MALIGNE: July 20-21, 1926, F. 
Neare, 19. 
BriTIsH COLUMBIA.—BIG ‘THOMPSON RIVER: 
June: 13; 31924 3°60 3 Oo PRINCE? GEORGE, 
Nechaka River: July 13-15, 1938, W. E. 
Ricker, 1¢6, 19, 1 exuvia. 
MANIToOBA.—CHURCHILL: July 9, 1936, H. E. 
McClure, 2¢, 59. 
MICHIGAN.—PEQUAMING: July 5, 1903, Mor- 
gan Hebard, 1¢. MONTMORENCY COUNTY, 
Hunt Creek, near lower end of swamp above 
County roads (612 saa prilasi4e 19305 i sanyy 
Leonard, 3 nymphs. GrayLinc, Manistee River 
near town: May 22, 1936, Frison & Ross, 3 
exuviae. MARQUETTE CouNTy, Yellow Dog 
River, near Route M-35: Sept. 6, 1937, J. W. 
Leonard, 8 nymphs. LAKE County, Pine River 
at. Walker. Bridge: —May 31,.°1938, Jay We 
Leonard, 14. Montmorency County, Pigeon 
River, 18 miles east of VANDERBILT: Oct. 24, 
1934, J. W. Leonard, 2 nymphs. SCHOOLCRAFT 
County, east branch of Fox River: Aug. 2, 
1935, J. W. Leonard, 2 nymphs.’ Honor, 
Platte River: May 27, 1939, Frison & Ross, 
3¢@ (reared), many exuviae. NIRVANA, San- 
Vol. 22, Ari 
born Creek: May 28, 1939, Frison & Ross, 
4 exuviae; May 10, 1940, Frison & Ross, 11 
nymphs. MaAyFIELD, Boardman River: May 
28, 1939, Frison & Ross, 1 exuvia. Pere Mar- 
quette River near BALDWIN: May 19, 1940, 
Frison & Ross, 19 and 1 exuvia (reared) ; 
May 9-10, 1940, Frison & Ross, 4 nymphs, 
BALDWIN, Pere Marquette River: May 28, 
1939, Frison & Ross, 6 exuviae; May 23, 1940, 
Frison & Ross, 19 and exuvia (reared). 
MonTMorENCY County, Hunt Creek: Aug. 
30-Sept. 3, 1940, J. W. Leonard, 1¢. 
MINNESOTA.—HENNEPIN CouNTy: May 11, 
192014" 
NEWFOUNDLAND.—West branch UPPER HuM- 
BER River, between falls: July 8, 1938, E. 
Colohan, 19. 
OREGON.—CorRVALLIS: Feb. 25, 1934, H. At 
Scullen, 1¢ ; March 14, 1934, K. Gray, 16; 
March 19, 1934, H. A. Scullen, 1¢, 19 ; March 
21, 1934, J. Roaf, 56, 19; March 135i 
Gray & Edwards, 12; March 28, 1933308 
Roaf, 1¢. Oregon State College campus, 
CorvaLLis: April 5, 1934, N. P. Larson, jis 
March 28, 1935, J. Schuh, 16; April 9, 1935, 
Dimick, 1¢; Agriculture Building, April 10, 
1935, 19; April 5, 1936, R. S. Rosenstiel, 195 
April 11, 1935, K. Gray, 19. GRANGER: April 
28, 1934, A. O. Larson; PGs 
QueEBEC.—MOonTREAL, Lake St. Louis near 
St. Bernard Island: June 30, 1941, N. La- 
lumiere, 46. LAURENTIDES NATIONAL PARK: 
G. Epaule Lake, Sept. 15-18, 1938, C. Gauthier, 
3 nymphs; Noel Lake, Sept. 16, 1938, C. 
Gauthier, 2 nymphs; Big Rock Lake, July 29, 
1938, Gauthier & Fournier, 2 nymphs, 2 exu- 
viae. 
WISCONSIN. — SPOONER, Namakagon River: 
April 29, 1939, Frison & Burks, 1¢, 29. 
Hydroperla subvarians (Banks) 
Perla subvarians Banks (1920, p. 317). 
Original description, ¢@, @. 
Needham & Claassen (1925) placed 
subvarians as a synonym of Perla postica 
Walker, but in view of Ricker’s (1938) 
notes regarding the type in the British 
Museum, it seems advisable to use the 
name subvarians for certain eastern and 
northeastern specimens of Hydroperla at 
least in part called P. postica since 1925. 
Ricker’s statement that the abdomen of 
the type is missing indicates that postica 
can never be recognized with certainty on 
the basis of the typic specimen alone. It 
is possible, however, that collecting along 
the MacKenzie River in northwestern 
Canada may some day provide esoteric in- 
formation which will establish its identity. | 
The typic series of subvarians, No. 
10,817, is in the Museum of Comparative 
Zoology, and consists of both males and 
females. One of the male cotypes bear- 
ing the labels “Great Falls, Va., 12-May, 
