September, 1942 
(they cannot be clearly seen).” In view 
of this suggestive description, it is surpris- 
ing that the name of nobilis was associated 
by Smith (1917) with a species which 
has the eighth abdominal sternite distinctly 
incised in the middle of its posterior mar- 
gin. Needham & Claassen (1925) fol- 
lowed Smith, and, previous to a close study 
of the types of nobilis, this use of names 
was accepted by me (1935a). 
In the Museum of Comparative Zo- 
ology, there are two specimens, one male 
and one female, labeled as the types of 
nobilis and assigned the type number of 
“241.” Upon two occasions I have studied 
these types in considerable detail, and upon 
another occasion had them independently 
studied for me by Dr. H. H. Ross of the 
linois Natural History Survey. The 
typic female specimen has associated with 
it on the insect pin the data, “P. nobilis 
Hagen-Winthem-Hagen,” and the typic 
male the data, “New York—Winthem- 
Hagen.” Neither the typic male nor the 
typic female corresponds to the use of 
nobilis as defined by Smith (1917) and 
followed by Needham & Claassen (1925) 
and subsequently by me (1935a). The 
typic female has the posterior margin of 
the eighth abdominal sternite straight and 
thus corresponds with the “truncated” 
part of Hagen’s original description and 
the species dorsata as now accepted. The 
“two short setiform appendages” question- 
ably mentioned by Hagen (1861) do not 
now show in the pinned specimen, and 
later Hagen (1873) states, “There are 
no appendages (as I described with a ? 
in my Synopsis). Even if these appen- 
dages were present, as I shall show in a 
following paragraph, they would not pre- 
clude this typic female being placed in the 
synonymy of dorsata. The typic male, 
likewise, has the lobes of the tenth ab- 
dominal tergite slightly turned upwards 
as in shelfordi Frison and dorsata, and 
most certainly not downwards as in nobilis 
as used by Smith (1917). Since all evi- 
dence points to the male and female speci- 
mens labeled as types ‘“‘No. 142” being the 
true types, it must follow that nobilis 
should be placed in the synonymy of 
dorsata. 
Unaware of certain characters of frigida 
Gerstaecker (1873) from Labrador, pre- 
viously sunk as a synonym of dorsata by 
Smith (1917), I described shelfordi in 
Frison: NortH AMERICAN PLECOPTERA 
243 
1934 from Fort Churchill on Hudson’s 
Bay. Ricker (1938), after a study of 
Gerstaecker’s type, came to the conclusion 
that shelfordi was a synonym of frigida, 
and I now accept the view that these two 
are of the same species. 
It is also now my view that shelfordi 
is the same as dorsata and that the differ- 
ences originally used by me (1934) to 
Fig. 1.— 
Pteronarcys 
dorsata. 
2 SUBGENITAL PLATE 
separate the two are attributable to vari- 
ation. ‘This view was gradually formed 
by the study of considerable adult Pteron- 
arcys material and by repeated attempts to 
Separate to species the nymphs belonging 
to this same complex of species (lacking 
lateral hooks on sides of abdomen). My 
suspicions that shelfordi (= frigida) in- 
tergraded with dorsata were definitely con- 
firmed by the rearing of a series of adults 
from nymphs found climbing out of the 
water in the Pere Marquette River near 
Baldwin, Mich., on May 19, 1940. Fig. 
1 shows the posterior margins of the eighth 
abdominal sternites of adult females reared 
at this time. It can be seen from this figure 
that there is intergradation in the same 
locality between females of the dorsata 
and shelfordi types, and they should not 
be accepted as distinct species. When 
shelfordi was originally described I was 
not aware of the shape of the eighth ab- 
dominal sternite in the females of frigida, 
and as a result of Smith’s (1917) paper 
I assumed that all the names placed in 
synonymy of dorsata referred to females 
having the posterior margin of the eighth 
abdominal sternite straight without small 
projections. 
Distributional records do tend to indi- 
cate, however, that specimens of dorsata 
having the eighth abdominal sternite 
straight are more nearly confined to the 
southern part of the range of this species, 
and those with two small projections on 
the eighth sternite (frigida and shelfordi 
types) prevail in the northern part of its 
range. 
