290 
fortunately, the holotypic male of bradley1 
has its abdomen missing, but Smith’s draw- 
ing of a side view of the paragenital plate, 
lateral stylets and supra-anal process of the 
typic male are sufficient to indicate their 
likeness with tibialis. In view of (1) the 
distributional range involved, (2) the 
agreement in gill arrangement, (3) the 
similarity of a female evidently belonging 
to tibialis with the allotype of bradleyt, 
(4) the general agreement of a drawing 
of certain genitalic structures of the typic 
male of bradleyi with the male of tzbzalis 
and (5) the overlooking by Smith of the 
species tibialis when describing bradleyt, 
I propose that bradleyi be placed in the 
synonymy of tibialis. 
Perlodes signata (Hagen) 
Dictyopteryx signata Hagen (1874, p. 575). 
Original description, ¢, Q 
Dictyopteryx irregularis Banks (1900, p. 
243). Original description, 2. Synonym. 
Perlodes yosemite Needham & Claassen 
(1925, p. 56). Original description, ¢, &. 
New synonymy. 
Smith (1917) placed irregularis in the 
synonymy of signata, but Needham & 
Claassen (1925) have treated the two as 
distinct. I have studied the types of both 
irregularis (M.C.Z. No. 1,130, @ ) and 
signata (M.C.Z. No. 244, 6, 9) and 
can find no good characters for their sepa- 
ration. The types of both species have a 
distinctly cleft subgenital plate in the fe- 
male, and both sexes have four pairs of 
gills: one pair attached to submentum and 
three pairs on sides of thorax. The differ- 
ence that Needham & Claassen (1925) 
mention in the shape of the tip of the 
genital hook of the males, in my opinion, 
is the result of individual variation. I 
have studied a male in the Cornell Uni- 
versity collection from Paradise Valley, 
Wash., July 17, 1920, collected by E. P. 
Van Duzee, which probably is the neallo- 
type of irregularis, not one of the original 
typic series, fixed by Needham & Claassen. 
This specimen was determined by Claas- 
sen as a male or irregularis and is in very 
poor condition. Enough remains to estab- 
lish that it has a gill arrangement similar 
to that of signata, and therefore I believe 
it is of this species. he parts of the 
genitalia are missing. 
Although the original description of 
yosemite states that the holotypic male 
Ittrnots NATURAL History SURVEY BULLETIN 
Vol..22, Arta 
and allotypic female are both in the collec- 
tion of the California Academy of Sci- 
ences, only the allotypic female could be 
located by the present Curator of Insects, 
Dr. E. S. Ross, when I recently visited 
the Academy to study the stonefly types 
deposited there. “he allotype of yosemite 
has a gill arrangement similar to that of 
signata, and the shape of the subgenital 
plate is of the same general type. The 
drawing of the subgenital plate by Need- 
ham & Claassen makes it appear that the 
two lobes of this plate are very angular 
or sharply pointed, whereas they are 
rounded. The characters mentioned in 
the original description to separate the 
male of yosemite from that of signata are 
ones which exhibit considerable variation 
in a series of specimens. I have no hesi- 
tancy in placing yosemite in the synonymy 
of signata. 
Of the species of Perlodes, signata is 
most frequently collected, and specimens 
are in the Illinois Natural History Survey 
collection from Alberta, British Columbia, 
Colorado, Montana, Oregon, Utah and 
Washington. 
Isogenus frontalis Newman 
Isogenus frontalis Newman (1838a, p. 178). 
Original description, 2. 
Isogenus colubrinus Hagen (1874, p. 576). 
New synonymy. 
In the Museum of Comparative Zool- 
ogy are the typic specimens of Isogenus 
colubrinus Hagen (1 male, No. 263), 
Isogenus elongatus Hagen (3 females, No. 
262), Perla incesta Banks (3 females, No. 
10,838) and Perla titusi Banks (1 male, 
No. 10,046). After a careful study of all 
these types and a large series of specimens 
of this genus in the Illinois Natural His- 
tory Survey collection, I have come to the 
conclusion that Needham & Claassen 
(1925) were correct in considering i- 
cesta and titusi as synonyms of frontalis. 
However, I dissent from Needham & 
Claassen (1925) in holding colubrinus 
as a distinct species and propose that 
it be placed in the synonymy of frontalis. 
I cannot find any differences between the 
type of colubrinus and reared females 
which can be accepted as frontalis. Fur- 
thermore, males from western states ass0o- 
ciated with females of the frontalis—colu- 
brinus type are similar to reared specimens 
