﻿A REVISION OF THE PALEOZOIC BRYOZOA 

 By E. O. ULRICH and R. S. BASSLER 



Part II.— Ox Genera and Species of Trepostomata 



We have no reason for emending the definition of the order Trepo- 

 stomata as given in previous works by the senior author. In order 

 to save repetition it is to be understood that, when no remarks follow 

 a family or generic name, we are satisfied with the diagnosis given 

 in the English edition of Zittel's Textbook of Paleontology or in the 

 Synopsis of American Fossil Bryosoa. 1 



The classificatory value of the structure of the walls separating 

 neighboring zooids, especially the degree in which the calcareous 

 investment of adjoining zooids is either amalgamated or maintains 

 for each its integrity, continues to impress us more and more favor- 

 ably. According as the walls are amalgamated or retain their duplex 

 character, the seven families recognized under the Trepostomata in 

 the latest classification of Paleozoic Bryozoa, fall four into the first 

 and three into the second division, as follows: (i) (Am alga mat a) 

 Monticuliporida, Hetcrotrypidec, Constcllariidce, and BatostomcUidcc ; 

 (2) (Integrata) AmplexoporidcB, Calloporidce, and Trematoporida. 



Division I. — AMALGAM ATA new division 

 Trepostomata in which the boundaries of adjacent zocecia are 



obscured by the more or less complete amalgamation of their walls. 

 In a few genera, notably Prasopora and Aspidopora, referred to 



families of this division, the amalgamation of the walls is sometimes 



difficult to establish. 



Family MOXTICULIPORIM; Nicholson (Emend. Ulrich) . 

 Genns Monticulipora D'Orbigny 



Our revised conception of Monticulipora is essentially as that pub- 

 lished in volume in of the Paleontology of Minnesota. However, 

 a few forms previously referred to the genus, principally because 

 there was no other group to receive them, are here removed to the 

 new genus Orbignyella. The peculiar granulose walls, the very 



l Bull. U. S. Geological Survey, No. 173. 



15 



