PREFACE. 



Since 19vU the junior author of this article has devoted much 

 time to the accumulation of Tertiary bryozoa, particular attention 

 being paid to material of this age from American localities. The 

 object of these efforts lay in the hope that sooner or later an oppor- 

 tunity might be offered to monogi-aph the subject. In the meantime 

 the value of the bryozoa for purposes of stratigraphic correlation was 

 recognized and this fact secured the active cooperation of several 

 members of the United States Geological Survey, notably Dr. T. 

 Wayland Vaughan. The collections resulting from these combined 

 efforts proved so large and numerous that it soon became evident 

 one person alone could not complete their study in a reasonable 

 length of time. Besides the intimate relationship of the Tertiary 

 bryozoa with the living forms required a good Imowledge of the 

 taxonomy and anatomy of the recent species on the part of the 

 student who attempted the description of the fossil forms. Fortu- 

 nately for the writer, Ferdinand Canu, of Versailles, France, well 

 known for his extensive and accurate work on Mesozoic, Cenozoic, 

 and Recent bryozoa, very kindly consented, in 1912, to join him in the 

 study of the American Cenozoic faunas, with the result that now, 

 after four years of work interrupted only by exigencies arising from 

 the great war, a monograph of nearly five hundred species of Lower 

 Tertiary Cheilostomata has been completed. As the publication of 

 this monograph will of necessity be slow, it has been thought advis- 

 able to precede it with the following brief synopsis of the classifica- 

 tion with description of the new genera and their genotypes. 



R. S. Bassler. 

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