270 
has considerably contributed to our knowl- 
edge of North American stoneflies. 
The morphological characters of rickert, 
excepting those in which it differs from the 
true pygmaea, have been fairly well cov- 
ered in my 1929 and 1935a papers under 
the name of pygmaea. It seems necessary 
JN 
SUPRA-ANAL PROCESS 
SHEATH 
C'ABDOMINAL SEGMENTS 
Q SUBGENITAL PLATE 3! 
Fig. 36—Allocapnia rickeri. 
to present here, therefore, only a brief 
review of the most salient characters need- 
ed for recognition of rickeri and new illus- 
trations for comparison with those of the 
true pygmaea. 
Mate.—Similar in general features to 
curiosa Frison as described in this paper. 
Certain characters peculiar to rickeri and 
separating it from other species are as 
follows: Wings short and usually extend- 
ing about half the length of abdomen; 
seventh abdominal tergite without sug- 
gestion of any tubercle, eighth tergite with 
two rather low and definitely separated 
tubercles, ninth and tenth tergites with 
middle area depressed and membranous 
for reception of supra-anal process; supra- 
anal process, fig. 36, with a short head. 
FEMALE.—Similar in most morphologi- 
cal features to the male. Wings reaching 
about to or slightly beyond tip of ab- 
domen; a wide, median, dorsal, longitudi- 
nal stripe extending from base of dorsum 
of abdomen to hind margin of eighth ter- 
cite, last two tergites entirely and darkly 
sclerotized; seventh and eighth abdominal 
sternites fused in middle and without 
Intinors NaturaL History SURVEY BULLETIN 
V ol. 22, Arte 
transverse membranous strip between 
them; subgenital plate shaped as in fig. 
36. 
Holotype, male. — Golconda, Big Grand 
Pierre River, Ill.: March 7, 1928, T. H. Frison 
& H. H. Ross. ; 
Allotype, female—Same data as for holo- 
type. 
Holotype and allotype represent a mating 
Dalit, 
Paratypes.—ILiinois.—Apple River, north- 
west of APPLE RIVER CANYON STATE PARK: 
March 2, 1938, Ross & Mohr, 1126, 279. 
BLOOMFIELD: March 7, 1928, on concrete 
foundation of bridge, Frison & Ross, 134, 
29. Drxon Sprincs: Feb. 2, 1934, Frison & 
Mohr, 54¢, 29, 1 mating pair. EICHORN: 
March 6, 1928, Frison & Ross, 424, 82 ; Buck 
Creek, on bridge, Frison & Ross, 216, 119. 
Gotconpa, Big Grand Pierre River, on and 
near bridge: March 7, 1928, Frison & Ross, 
754, 329, 4 mating pairs. GorHAM: Feb. 3, 
1934, Frison & Mohr, 16, 19. HERop: Gib- 
bons Creek, under bark of tree hanging over 
stream, March 6, 1928, Frison & Ross, 323 
Gibbons Creek, on stones and debris in and 
near margin of stream, 476, 309, 1 mating 
pair; April 19, 1937, Ross & Mohr, 19; Rose 
Creek, foundation of concrete bridge, March 
6, 1928, Frison & Ross, 1 mating pair; Big 
Grand Pierre River, foundation of concrete 
bridge, March 6, 1928, Frison & Ross, 1g 
HEROD-ELIZABETHTOWN, Hicks Branch Creek: 
March 6, 1938, Frison & Ross, 3¢. JONESBORO: 
Feb. 3, 1934, Frison & Mohr, 504, 42. NEw 
CotumsiA, Clifty Creek: Dec. 26, 1932, Harp- 
er,4¢. Tueses: Feb. 3, 1934, Frison & Mohr, 
42. VIENNA, on concrete foundation of bridge: 
March 7, 1928, Frison & Ross, 16. WARREN, 
tributary of Apple River: March 2, 1938, Ross 
& Mohr, 1114, 89. 
Other specimens of this species examined, 
but not included in paratypic series, are as 
follows. 
ILLINOIs.—GoLconpba, Big Grand Pierre 
River: March 7, 1928, Frison & Ross, many 
nymphs. 
DIsTRICT OF COLUMBIA.—WASHINGTON, Po- 
tomac River: Feb. 5, 1938, Gurney & Burks, 
1¢. 
INDIANA.—BACON: creek southwest of town, 
Feb. 14, 1938, Frison & Mohr, é dé, 9 Same 
mating pairs; Patoka River northwest of 
town, Feb. 14, 1938, Frison & Mohr, 46, 
99. ENGLIsH, creek north of town: Feb. 44, 
1938, Frison & Mohr, 66, 29, 1 mating 
pair. McCormick CREEK STATE PARK: March 
14, 1936, Frison & Ross, 6 6, 9 9. MARENGO, 
creek west of town: Feb. 14, 1938, Frison & 
Mohr, & 4, 29. Mepora, creek northwest of 
town: Feb. 14, 1938, Frison & Mohr, 2¢ 
MILLTowN, creek west of town: Feb. 14, 1938, 
Frison & Mohr, 84, 19. NEEDMORE, creek 
near town: March 14, 1936, Frison & Ross, 
&é, 29, 3 mating pairs. PALMYRA, Blue 
River north of town: Feb. 14, 1938, Frison & 
Mohr, @¢, 22. Paowt, south of town: Feb. | 
14, 1938, Frison & Mohr, 66, $% Q, many 
mating pairs. SALEM, river south of town: 
