﻿American Palaeozoic Fossils. 



47 



Tangential sections (PL III., fig. 3) show that the zooecia are cir- 

 cular or ovate, thin-walled, and separated by a single series of large 

 angular interstitial vesicles, a number of which at sub-regular intervals 

 form groups that represent the maculae observed on the surface of the 

 zoarium. Just below the surface the interstitial vesicles, though still 

 recognizable, are filled by an apparently homogenous deposit. 



In vertical sections (PI. III., fig. 3a) the zooecial tubes are at first 

 prostrate, then gradually l3ent upward until they are nearly perpen- 

 dicular; anterior wall more or less flexuous; diaphragms horizontal, a 

 tube diameter or less distant from each other. Vesicular interstitial 

 tissue composed of comparatively large vesicles, which are more or less 

 obscured near the surface by a secondary depos it. 



This is a fine species, and readily distinguished from the associated 

 Lichenalia species by its lobate or utricular growth, and if that fails, 

 by its circular, uninflected cell apertures and concave interspaces. 



Formation and locality: Common in the Kaskaskia Group, at Tate- 

 ville, Litchfield, and other localities in Kentucky. 



Fistulipora (?) clausa, n. sp. (PI. III., figs. 4, 4a, 46.) 



Zoarium consisting of compressed branches, two inches or more in 

 height, from 0.2 to 0.6 of an inch in width, and from 0.07 to 0.15 of 

 an inch in thickness. At intervals of about 0.18 inch, measuring 

 from center to center, the surface exhibits sub-stellate maculae, 

 between which the zooecia are uniformly distributed in very regular 

 oblique series, so that ten occur in the length of 0.2 inch; in the im- 

 mediate vicinity of the smooth maculae the furrows separating the 

 series of cells are usually widest. In the younger examples the 

 zooecial apertures are elliptical or circular, and oblique, the posterior 

 margin being prominently elevated; the orifice is in many specimens 

 closed by an operculum, with a rather large perforation extending from 

 the center of the lid to near the lower margin. With age the aper- 

 tures gradually become more direct and smaller, until they are com- 

 pletely closed by a thin membraneous, apparently imperforate covering, 

 beneath which they are still to be recognized, their positions being 

 marked by small papillae. Interstitial spaces flat or slightly con- 

 cave, usually smooth, frequently very minute^ pitted or granulose. 



Tangential sections (PI. III., fig. 4a) passing through the zoarium 

 just below the surface show that the interstitial spaces are occupied 

 by a dense deposit. My tangential sections do not show positively 



