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A REVISION OF THE ORDOVICIAN BRYOZOAN 



GENERA BATOSTOMA, ANAPHRAGMA, 



AND AMPLEXOPORA 



By RICHARD S. BOARDMAN 



Associate Curator of Geology 



United States National Museum 



Smithsonian Institution 



(With Seven Plates) 

 INTRODUCTION 



The genera Batostoma Ulrich, 1882, Anaphragnia Ulrich and 

 Bassler, 1904, and Amplexopora Ulrich, 1882, all belong to the order 

 Trepostomata of the Bryozoa. The three genera are here grouped 

 together merely as a convenience in discussing their mutual prob- 

 lems. The grouping does not necessarily imply close taxonomic re- 

 lationships among the genera. 



The genera Batostoma and Anaphragnia are placed in the family 

 Trematoporidae Ulrich in Miller, 1889 (Bassler, 1953, p. G113). 

 Batostoma is a fairly common genus in Middle and Upper Ordovician 

 rocks of North America. Anaphragnia is known only from rocks of 

 Richmond age in North America and highest Middle and Upper Or- 

 dovician rocks in Estonia, Anaphragnia was described originally as, 

 "agreeing in all essential respects with Batostoma Ulrich, except that 

 both the zooecial tubes and mesopores are entirely devoid of dia- 

 phragms" (Ulrich and Bassler, 1904, p. 49). Based on the study of 

 newly made thin sections of types, all internal characters of generic 

 value are interpreted here to be dissimilar in the two genera (see 

 p. 12). 



The genus Amplexopora is the type genus of family Amplexopori- 

 dae Ulrich in Miller, 1889. Restudy of the primary types in the U. S. 

 National Museum collection resulted in approximately half of the 

 species previously placed in Batostoma being reassigned to Am- 

 plexopora, and this in turn doubled the number of species of Am- 

 plexopora in the collection. If these reassignments prove to be valid, 



SMITHSONIAN MISCELLANEOUS COLLECTIONS, VOL. 140, NO. 5 



