PREFACE. 
xv 
use of some interesting specimens of recent collection and information concern¬ 
ing certain horizons in the Lower Carboniferous strata, and also the abundant ma¬ 
terial of his earlier collection; from Prof. E. W. Claypole, the use of specimens, 
as well as information concerning the geological relations of certain species; 
from Pres. E, S. Brainerd and Prof. H. M. Seely, of Middlebury College, Vt., 
the use of specimens from the Calciferous horizon, which have since been 
donated to the State Museum ; from Prof. Geo. H. Perkins, of the University 
of Vermont, the use of specimens; from E. E. Teller, of Milwaukee, Wis., 
and F. A. Sampson, of Sedalia, Mo., similar favors. Acknowledgments are 
further due to Mr. F. A. Blair, of Sedalia, Mo., and Dr. J. H. Britts, 
of Clinton, Mo., for the use of specimens and especially for a collection 
of Choteau limestone fossils from the former; also to W. H. E. Lykens, 
S. J. Hare, F. W. McIntosh, of Kansas City, for specimens of Coal Meas¬ 
ure fossils; also to Prof. Thomas B. Stowell, of Cortland (now of Potsdam), 
N. Y., W. L. Brownell and D. S. Chatfield, of Syracuse, and E. B. Knapp, of 
Skaneateles. To Prof. B. K. Emerson, of Amherst, Mass.; to Dr. C. E. 
Beecher, of New Haven, Conn.; and to E. 0. Ulrich, of Newport, Ky., thanks 
are due for specimens and information ; also to W. T. Knott, of Lebanon, and 
Mr. E. C. Went, of Frankfort, Ky.; to Prof. William Libbey, of Princeton, N. J., 
through Moritz Fischer; Prof. Joseph Moore, of Earlham College, Richmond, 
Ind.; to Col. C. C. Grant, an old and valued correspondent, and Mr. William 
Turnbull, of Hamilton, Ontario, and to Mr. B. E. Walker, of Toronto, for speci¬ 
mens from the Niagara and Hudson River groups; to Professors Oliver Marcy, 
of Evanston, Ill., Edward M. Shepard, of Springfield, Mo., W. H Barris, of 
Davenport, la., and S. S. Gorby, State Geologist of Indiana; to L. A. Cox and 
D. G. Anderson, of Keokuk, la., for brachiopods of the Keokuk group, presented 
by them to the State Museum ; to R. R. Rowley, of Curryville, Mo.; to Miss 
Mary E. Holmes, of Rockford, Victor E. Phillips, of Olney, and J. H. South- 
well, of Rock Island, and to W. R. Head, H. H. Hindshaw, and Victor C. 
Alderson, of Chicago, Illinois. 
Among foreign friends and correspondents, my first acknowledgments are due 
to the late Thomas Davidson, of Brighton, England, for many years of personal 
