﻿ULRICH BASSLER] REVISION OF PALEOZOIC BRYOZOA 43 



AMPLEXOPORA CYLINDRACEA new species 



(Plate XIII, 5. 6; Plati XIV, 4, 5) 



This species resembles the lasl two considerably in interna] char- 

 acters, but as it has a decidedly different method of growth, besides 

 several minor peculiarities and, moreover, marks a lower geological 



horizon, we have decided to recognize it as a distincl -pi lies. 



Compared with . /. ampla, the zoarium of . /. cylindracea, consisting 

 of straight, infrequently-branching, narrow, cylindrical stems, 5 or 

 6 mm. in diameter, is readily distinguished from the short, thick, 

 frequently-branching stems of that species. The rounded masses of 

 A. coluuibiana are too different externally to he confused with either 

 of the two species. 



Occurrence. — Abundant in the lower part of the Catheys limestone 

 of the Trenton at Nashville. Tennessee. Here it occurred in a shaly 

 bed containing many other bryozoa and an abundance of Orthorhyn- 

 chida linneyi (Nettleroth). 



Cat. No. 43,126, U. S. N. M. 



Genus Monotrypella Ulrich 



This genus should be restricted to the genotype, M. aqualis 

 Ulrich, and such other ramose Amplexoporidce as differ from 

 Amplexopora only in wanting acanthopores. Of described species 

 that have been referred to Monotrypella, it is doubtful if any but 

 Edwards and Haime's Monticulipora pulchclla, as redefined by 

 Nicholson under the name Monotrypa pulchella, can maintain its 

 position in this genus. The Devonian Monotrypella simplex Ulrich 

 has amalgamated walls and must, therefore, be assigned to some 

 other genus. 



We are not yet prepared to name the genus to which M. simplex 

 should be referred, nor even to decide definitely the family. In fact, 

 aside from a species or two undoubtedly referable to Batostomella and 

 the Batostomella obliqua Ulrich, in which we now see an Erido- 

 trypa, the Devonian Trepostomata are very difficult to classify. 

 Mewed collectively, they seem to form a group of Amalgamata by 

 themselves, with varying relations to Monticuliporidce, Heterotry- 

 pidce, and Batostomellithe. Studied individually, first one, then 

 another of these relations seems to be the dominant one. with the 

 result that closely allied species may be widely separated in their sys- 

 tematic arrangement. To secure a more natural and stable classifi- 

 cation it is necessary to study the Devonian Trepostomata first as a 

 whole and then no less carefullv in connection with their Silurian 



