236 
numerous species, the synonymy of certain 
species with others and the discovery of 
new species. In the present paper are the 
most important of these findings, with 
special emphasis upon a complete account 
of the fauna of [llinois. 
Acknowledgments 
I am indebted to many individuals and 
institutions for the donation or loan of 
material upon which this paper in part is 
based. Specimens of special importance 
have been donated or loaned by the follow- 
ing: Nathan Banks and F. M. Carpenter, 
Museum of Comparative Zoology, Cam- 
bridge, Mass.; J. Chester Bradley, C. 
McC. Mottley, J. G. Needham and 
Henry Dietrich, Cornell University, Itha- 
ca, N. Y.; Gordon B. Castle, Montana 
State University, Missoula, Mont.; A. C. 
Cole, Jr., University of Tennessee, Knox- 
ville, Tenn.; E. T’. Cresson, Jr., Academy 
of Natural Sciences of Philadelphia, Phil- 
adelphia, Pa.; K. C. Emerson, Oklahoma 
Agricultural and Mechanical College, 
Stillwater, Okla.; P. W. Fattig, Emory 
University, Atlanta, Ga.; A. B. Gurney, 
U. S. Bureau of Entomology and Plant 
Quarantine, Washington, D. C.; John F. 
Hanson, Massachusetts State College, 
Amherst, Mass.; P. H. Harden, Univer- 
sity of Minnesota, St. Paul, Minn. ; ‘Thel- 
ma Howell, Wesleyan College, Macon, 
Gar P)-|eesennings, "Brooklyn; Nox; 
Stanley G. Jewett, Jr., Portland, Ore. ; 
D. E. Kimmins, British Museum, London, 
England; Trevor Kincaid and Melville 
H. Hatch, University of Washington, 
Seattle, Wash.; Willis King, National 
Park Service, Gatlinburg, Tenn.; G. F. 
Knowlton, Agricultural Experiment Sta- 
tion, Logan, Utah; Mitsuko Kohno, Wa- 
kamatsu, Japan; J. W. Leonard, Institute 
for Fisheries Research, University of 
Michigan, Ann Arbor, Mich.; F. Earle 
Lyman, University of Michigan, Ann 
Arbor, Mich.; C. E. Mickel, University 
of Minnesota, St. Paul, Minn.; D. C. 
Mote and R. L. Post, Oregon State Agri- 
cultural College, Corvallis, Ore.; Ferris 
Neave, Pacific Biological Station, Nanai- 
mo, B. C., Canada; A. Colin Nicol, Uni- 
versity of Western Ontario, London, 
Ont., Canada; W. E. Ricker, Indiana 
University, Bloomington, Ind.; H. G. 
Rodeck, University of Colorado, Boulder, 
Ittinors NATURAL History SURVEY BULLETIN 
Vol. 22, Art.@ 
Colo.; W. M. Sprules, University of 
Toronto, Toronto, Ont., Canada; W. C. 
Stehr, Ohio University, Athens, Ohio; 
M. C. Tanner, Ogden, Utah. 
H.-H.. Ross, B. D. Burks, Gage 
Riegel and K. M. Sommerman, all staff 
members of the Insect Survey Section of 
the Illinois Natural History Survey, have 
ereatly aided the preparation of this re- 
port by the collection of material, sorting 
and labeling of material and in numerous 
other ways. J. S. Ayars, Editor of the 
Survey, has materially assisted with the 
final reading, preparation and styling of 
this article. 
I am particularly indebted, however, to 
C. O. Mohr, Associate Entomologist with 
the Survey, for almost all the splendid 
drawings which illustrate this article. 
Good drawings of the important structural 
details of the adult and nymphal stoneflies 
and dorsal views of the nymphs are, in 
certain respects, better for identification 
purposes than are word descriptions. Be- 
cause of the excellent quality of these 
drawings, I have leaned heavily upon 
them in the writing of the descriptions. 
Disposition of Material 
All holotypes, allotypes and some of the 
paratypes of the species described as new 
in this article are deposited in the inseci 
collection of the Illinois Natural History 
Survey at Urbana. Paratypes of some 0: 
the species are deposited elsewhere, as indi 
cated in the typic records. | 
Much of the material listed in thi 
paper is in the collection of the Llinoi 
Natural History Survey. In some, bu 
not all, instances in which material is 1 
collections other than that of the Surve: 
that fact is indicated, the following ab 
breviations being used for institutional col 
lections. | 
M.C.Z.—Museum of Comparative Zool 
ogy of Harvard College, Cambridge 
Mass. 
C.U.—Cornell University, Ithaca, N. Y. 
A.N.S.—Academy of Natural Sciences 0 
Philadelphia, Philadelphia, Pa. | 
Arrangement of Subject Matter | 
In order to prevent treating variov 
genera in two separate portions of th 
article, I have interwoven the subje¢ 
