﻿SS 



Cincinnati Society of Natural History. 



four, and where the branch has a width of 0.18 inch, there are nine 

 vertical series. 



The internal characters are, on the whole, veiy much like those of 

 C. occelata, the type of the genus, and do not demand detailed 

 description. In tangential sections (PL II., fig. 4c), just below the 

 surface, the inter-zooecial spaces are fineh T lined. At a deeper level 

 the vesicular tissue is brought to view. The vesicles, like everything 

 else pertaining to the species, are arranged in longitudinal series. 



This species is readily distinguished from both C. occelata, Ulrich, 

 and C. carbonaria, Meek, by the more widely separated zooecia, and 

 distinct longitudinal ridges and furrows, which mark the surface. 

 From C. parallela, Phill., it differs in having from eight to ten rows of 

 cells; that species has only four or five. In all other respects they are 

 closely allied. 



Formation and locality: This is a common species in the St. Louis 

 and Keokuk groups of the Lower Carboniferous. My types are from 

 the Keokuk beds at King's Mountain tunnel, on the Cincinnati South- 

 ern Railroad. 



Coscinium, Keyserling, 1846. 



This genus possesses all the essential characters of the Cystodicty- 

 onidce, and differs from Cystodictya, somewhat in cell-structure, but 

 mainly in the form of the zoarium. Coscinium cyclops, Keyserling, 

 the type of the genus, also occurs in America, and is not an uncom- 

 mon fossil in the Upper Helderberg limestone near Louisville, Ky. A 

 tangential section of this species is represented by fig. 6, on Plate II 

 Such sections show that the inter-zocecial spaces are occupied by 

 smaller cells, whose vesicular form is demonstrated b}' vertical sec- 

 tions. Just below the surface the vesicular tissue is not apparent, 

 here being filled by a secondary deposit, that is perforated by a great 

 number of minute vertical canals. As is clearly shown in some 

 sections, these canals consist of two kinds, large and small, the latter 

 most numerous, but often destroyed during the process of fossilization. 

 (This, unfortunately, was the case in the section figured, which, at the 

 time I prepared the plate, was the best I had.) The cells have all the 

 characteristic features of the family. The generic characters of Cos- 

 cinium are briefly as follows: 



Zoaria forming thin flattened expansions, composed of branches 

 which inosculate at short intervals, till there is produced a broad frond 



