2 PROCEEDINGS OF THE NATIONAX. MUSEUM vol.69 



to evolve a natural classification based upon all the functions men- 

 tioned above. Our work upon the genera of Cheilostomata has pro- 

 ^rressed to such a point that we now feel justified in offering the pres- 

 ent classification and alphabetic list of genera for the benefit of stu- 

 dents in this subject. 



In our monographs of 1920 and 1923 upon North American 

 Tertiary Bryozoa we have published descriptions and text figures of 

 many genera of Cheilostomata. In addition to a general classifica- 

 tion and alphabetic list, we now present descriptions of some new 

 families and genera which are more fully elaborated and illustrated 

 \v works now in preparation. In cases where we are in doubt re- 

 garding the classification of a genus, the genotype and original ref- 

 erence are given. In all other instances we give only the date since 

 the literature is cited in the Synopsis of American Fossil Bryozoa 

 by Nickles and Bassler^ and in our monographs of Early Tertiary 

 Bryozoa ^ and Later Tertiary and Quaternary Bryozoa.^ 



DESCRIPTIONS OF FAMILIES AND GENERA 



Order CHEILOSTOMATA Busk 

 Suborder Anasca Levinsen 



Division 1, MALACOSTEGA Levinsen 



Family BIFLUSTRIDAE Smitt, 1872 



Membraniporae without ovicells. The zooecia are rectangular 

 (seen on their dorsal face). No spines. 



In this family we classify all the genera of the first group of Mem- 

 braniporae as we divided them in 1920 (p. 85), except Discoflustrel- 

 laria D'Orbigny, 1853, which we now refer to the family 

 Mamilloporidae. 



In addition to these genera we also refer Quadricellaria D'Orbigny, 

 1851, Cellarlnidra new name and Mevibraniporina Levinsen, 1909, 

 to the family. 



Genus CELLARINIDRA, new name 



(Cellarina D'Orbigny, 1851, preoccupied) 



The zoarium is articulated; the segments are cylindrical with 

 cells on all the faces. The zooecia have a cryptocyst more or less 

 developed and angular; the opesium is elliptical. There are small 

 interopesial avicularia. 



Genotype. — C ellarinidra {Cellarina) clavata D'Orbigny, 1851. 

 Cretaceous. 



> 1900. Bulletin 173, U. S. Geological Survey. 

 » 1920. Bulletin 106, U. S. National Museum. 

 3 1923. Bulletin 125, U. S. National Museum. 



