﻿46 Cincinnati Society of Natural History. 



about nine occur in the space of 0.2 inch. Interstitial spaces, in the 

 worn condition, smooth; but in a good state of preservation show 

 small irregular pits. At intervals of two or three-tenths of an inch 

 the surface presents comparatively large, sometimes slightly elevated, 

 substellate "maculae." These, though varying more or less in size 

 and distribution, are still a characteristic feature of the species. 



Tangential or transverse sections (PI. III., fig. 2) show that the 

 zooecia have thin walls, that they are subcircalar, and separated by a 

 space equalling or slightly exceeding their diameters; each is sur- 

 rounded by a row of the small angular interstitial vesicles, so that 

 there exist two series of the latter between an}' given pair of the 

 former. The maculse are distinct in these sections, being composed 

 of a large number of the small interstitial cells. 



In longitudinal sections (PI. III., fig. 2a) the tube walls are thin 

 and comparatively straight; at intervals of about a tube diameter the 

 zooecial cavity is traversed by diaphragms. The vesicles in the inter- 

 stitial spaces are small, and form a closety woven tissue. 



The small size of the interstitial vesicles, and the closely woven tis- 

 sue formed by them, are the principal distinctive features of the 

 species. 



Formation and locality: In the St. Louis Group of the Lower Car- 

 boniferous, near Colesburg, Ky. 



Fistulipora excelens, n. sp. (PI. III., figs. 3, 3a, 36.) 



Zoarium irregularly lobate, occasionally sub -ramose, with internal 

 cavities lined by an epithecal membrane, or forming thin expansions, 

 with the lower side irregularly striated, both radially and concen- 

 trically; actual thickness, so far as observed, never exceeding 0.4 inch, 

 usually less than.0.2 inch. Zooecia regularly arranged in series, with 

 apertures circular, l-90th to l-80th of an inch in diameter, and margined 

 by a distinct, nearly equally elevated peristome. At intervals of 0.15 

 inch, more or less, the surface presents small, substellate maculae, from 

 which the zocecia appear to radiate in all directions; in the immediate 

 vicinity of the maculse they have larger and more oblique apertures; 

 in the intermediate areas five cells are ranged in 0.1 inch. Inter- 

 zooecial spaces usualty of less width than the diameter of the cell 

 aperture, concave, generally smooth and solid, sometimes, apparently, 

 minutely pitted. The last character is very likel} 7 deceptive, as the 

 interstitial spaces of the same specimens, when greatl} 7 magnified, 

 seem to be smooth. 



