68 TRENTON PERIOD. 



vertical walls, which gives them the appearance of being slightly convex ; 

 some ten or twelve rays, or dissepiments, extend iipon the sm-face of each 

 diaplu-agm, from the walls to its center ; walls well developed and vertically 

 striated as if by undeveloped rays. 



I am unable to perceive any specific difference between the specimens 

 contained in the collections and those which I have collected from the 

 localities that furnished Professor Hall with the type-specimens of the 

 species. 



Not having the means at hand for making a critical investigation of 

 the grounds upon which Edwards and Haime referred this species to Colwn- 

 naria alveolata Goldfuss, rejecting both the genus and species as established 

 by Professor Hall, I make use of the names given by the last-named 

 author. I do this with little hesitation, not only for the reason just 

 stated, but also because the fossil under consideration is widely known and 

 generally recognized by that designation among American geologists. 



The specimens of the collection are all silicified, by which means they 

 have lost some of their finer markings and details of structure ; but a few of 

 the cells are in a fine state of preservation. 



Position and localiiy. — Strata of the Trenton period, Cincinnati epoch ; 

 Silver City, New Mexico. 



Family CYATHOPHYLLID^. 



Genus ZAPHRENTIS Rafinesque et Clifford, 1820. 



Zaphrentis (?). 



Some specimens of Zaphrentis were also obtained from the sti-ata of 

 the Cincinnati epoch, at Silver City, New Mexico. They are either too 

 imperfect or possess too few characters to distinguish them specifically, and 

 they are noticed only for their generic value in a faunal summary of the 

 strata of that region that I have referred to the Trenton period. 



