NORTH AMERICAN EARLY TERTIARY BRYOZOA. 



By FERDINAND CANU, 

 of Versailles, France. 



AND 



RAY S. BASSLEK, 

 of Washington, District of Columbia. 



INTRODUCTION. 

 PREPARATION AND SCOPE OF THE WORK. 



Although the great abundance and splendid preservation of the bryozoa in the 

 Tertiary rocks of the Atlantic Coastal Plain and the Gulf region have been known 

 to students since early in the last century, so little attention was paid to this class 

 of organisms that the publications upon them number scarcely more than a dozen. 

 Moreover these, with a very few exceptions, give so imperfect an idea of the com- 

 paratively few species described that the field of American Tertiary bryozoology 

 may be considered as almost a virgin one. 



Upon his appointment to the division of paleontology in the United States 

 National Museum in 1901, the junior author of this monograph began to accumulate 

 collections of American Tertiary bryozoa. In a few years sufficient material had 

 been assembled and studied in a preliminary way to prove the great value of these 

 organisms in the most detailed stratigraphic correlation. When it is known that 

 at many localities exposing Tertiary strata the bryozoa are practically the only 

 fossils to be found, the need of this systematic study, if only for correlation pur- 

 poses, is apparent. 



In 1907 when the Coastal Plain Investigations of the United States Geological 

 Survey were reorganized with Dr. T. Wayland Vaughan in charge, the active 

 cooperation of Doctor Vaughan and his assistants was secured in furthering the 

 collecting of bi\yozoa. By 1912 the collections resulting from these combined 

 efforts had become so large and numerous that the Director of the Geological Survey, 

 upon the recommendation of Doctor Vaughan. proposed that the materials be made 

 the subject of a monograph. The junior author assented to the plan but soon found 

 that one person alone could not hope to complete the necessary work in a reasonable 

 length of time. Besides, the intimate relationship of the Tertiary bryozoa with 

 the living forms required a good knowledge of the taxonomy and anatomy of the 

 recent species on the part of the student who attempted the description of the fossil 

 forms. With the consent of the Geological Survey authorities the junior author 

 thereupon proposed to Ferdinand Canu, of Versailles, France, whose studies had 

 been mainly on the Tertiary and Recent bryozoa of Europe and South America, to 



55899 19 Bull. 106 1 1 



