14 AMERICAN FOSSIL BRYOZOA. [bull. 173. 



While there is general agreement as to the suborders and higher 

 groups, confusion reigns in the arrangement of the genera into fami- 

 lies, more especially of the post-Paleozoic forms. This is due in large 

 measure to the fact that the importance of the various structural fea- 

 tures is very differently rated. Formerly most writers considered 

 zoarial features of chief est importance for famil}^ and generic group- 

 ings, but of late there has come substantial agreement that zooecial 

 features far outweigh zoarial characters for classificatory purposes. 

 But as to the relative importance of the various zoa?cial characters 

 there is no agreement. A great deal of study is still required, espe- 

 ciall}' to determine the relationship of Paleozoic to later forms, before 

 the principles of classitication applicable to this class shall be so well 

 established that a classification can be made which will be correct 

 phy logenetically . 



OUTLINE OF CLASSIFICATION. 



The suljordination of the larger groupings of the brj^ozoa is shown 

 in the tabular form following: 

 Subkingdom Molluscoidea. 

 Class Bryozoa Ehrenbcrg. 



Group EcTOPROCTA Nitsche, 



Order Gymnolaemata Allman. 



Suborder I. Ctenostomata Busk. 

 Suborder II. Cyclostomata Busk. 

 Suborder III. Trepostomata Ulrich. 

 Suborder IV. Cryptostomata Vine. 

 Suborder V. Chilostomata Busk. 

 Group Entoprocta Nitsche. 



Order Pedicellinea Hincks. 

 Subclass Rhabdopleurae Gill. 



Order Podostomata Lankester. 



SCHEME OF CLASSIFICATION OF PALEOZOIC BRYOZOA. 



Subkingdom MOLLUSCOIDEA. 



Class BRYOZOA Ehrenberg. 



Group ECTOPROCTA Nitsche. 



Order GTMNOLUMATA Allman. 



Suborder Ctenostomata Busk. 



Family Rhopalonariidae. 

 Rhopalonaria Ulrich. 



Family Ascodictj'^onidje Ulrich. 



Ascodictyon Nicholson and Etheridge, Jun., Vinella Ulrich. 



