NORTH AMERICAN LATER TERTIARY AND QUATERNARY 
BRYOZOA. 
By Ferdinand Canu, 
Of Versailles, France, 
AND 
Ray S. Bassler, 
Of Washington, District of Columbia. 
INTRODUCTION. 
The present volume contains the results of researches upon the Post-Oligocene 
fossil bryozoa of North America and forms the concluding part of our studies upon 
the Tertiary and Quaternary faunas, those of the Eocene and Oligocene epochs 
having been published in 1920 under the title of North American Early Tertiary 
Bryozoa. 1 The present work, like the companion volume on the Early Tertiary 
faunas, was undertaken under the joint auspices of the United States Geologica 
Survey and the United States National Museum. Almost without exception all 
the type specimens described and illustrated in the present volume are contained 
in the paleontological collections of the United States National Museum. 
The authors are deeply indebted to Dr. Charles D. Walcott, Secretary of the 
Smithsonian Institution, and Mr. W. deC. Ravenel, Administrative Assistant in 
charge United States National Museum, who have arranged for the publication 
of the work and have extended various courtesies to us during its preparation. 
Dr. T. Wayland Vaughan, of the United States Geological Survey, has likewise 
spared no effort in assisting us to bring the work to a successful conclusion and 
we are greatly indebted to him, as well as to other members of the Federal Survey, 
particularly Mr. Wendell C. Mansfield, Mr. R. D. Mesler, and Mr. I. B. Milner. 
We are under many obligations to Mr. F. Julius Fohs, chief geologist of the 
Humphreys Mexia Oil Company at Mexia, Texas, who has very generously as¬ 
sisted us financially in the preparation and illustration of the volume, and who 
has thus shown his appreciation of the value of the bryozoa in stratigraphic and 
economic work. 
Through several grants from the Marsh Fund of the National Academy of 
Sciences and from the American Association for the Advancement of Science we 
have been able to carry on supplementary studies of other fossil and recent 
brvozoan faunas which were quite necessary in the preparation of this volume. 
For this assistance we are highly grateful, as we have thus been enabled to pursue 
our researches on a larger scale and to secure more definite and lasting results. 
i Bulletin 106, U. S. National Museum, 2 vols., 879 pp., 162 pis. 
1 
