NORTH AMERICAN LATER TERTIARY AND QUATERNARY 



BRYOZOA. 



By Ferdinand Canu, 



Of Versailles, France, 

 AND 



Ray S. Bassler, 



Of Washington-, District of Columbia. 



IXTRODUCTION. 



The present volume contains the results of researches upon the Post-Oligocene 

 fossil bryozoa of North America and forms the concludmg 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.i 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 durmg its preparation. 

 Dr. T. Wayland Vaughan, of the United States Geological Survey, has llke^^^se 

 spared no effort in assisting us to bring the work to a successful conclusion and 

 we are crreativ indebted to him, as well as to other members of the Federal Survey, 

 particufarly Mr. Wendell C. Mansfield, Mr. R. D. Mesler, and Mr. I. B. Milner 



We are under many obligations to Mr. F. Julius Fobs, 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 ot 

 Sciences and from the American Association for the Advancement of Science we 

 have been able to carrv 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 pureue 

 our researches on a larger scale and to sec ure more definite and lasting results. 



> Bulletin 108, U. S. National Museum, 2 vols., 879 pp., 162 pis. 



