254 Cincinnati Society of Natural History. 
as I now know; having since been very successful in preparing sec- 
tions of these forms, that such cells are numerously present in both of 
those species. I would also have better understood the relations of 
what I then called pseudo-septa,* as I could not have failed to see 
that they are produced by the. projection of the spiniform tubuli into 
the visceral cavity of the zoccia. z 
Formation and locality: . Cincinnati group. Not uncommon on the 
hills back of Covington, Ky., and Cincinnati, O., at an elevation of 
from 300 to 325 feet above low water mark in the Ohio river. 
ATACTOPORELLA MULTIGRANOSA, Ulrich (PI. XII, figs. 8, 8a). 
Atactopora multigranosa, Ulrich, Jour. Cin. Soc. Nat. Hist., vol. ii., p. 122, Pl. XIT., 
figs. 1,la. 
Zoarium usually attached to species of Orthoceras, often consisting 
of several layers, when tie whole surface may become irregularly 
undulating, or even lobate. The maximum thickness of each layer is 
about .06 of an inch. In younger specimens the surface is studded 
with small conical monticules, quite regularly arranged in series, at 
distances apart of about .08 of an inch, measuring from center to 
center. In older examples the regularity of their arrangement is 
somewhat impaired by the general inequalities of the surface. In all, 
the monticules carry cells with apertures but slightly, if at all, larger 
than those of the ordinary size, but the interstitial spaces are always 
appreciably thickened, and for that reason, when a little worn, the 
monticules appear to have subsolid apices. The cell structure in 
young and fully matured examples is quite different. In the new 
layers and young specimens generally, the interspaces between the 
cell-apertures are considerably wider than they are in the matured 
layers, being quite solid, and comnaratively thin in the latter. This is 
due to the fact that the interstitial cells are to a great extent 
suppressed, and filled up by a deposit of sclerenchyma, just as the 
zoarium enters the fully matured stage. In all cases the interstitial 
cells are either not at all to be detected, or they are very much 
obscured by the excessively numerous and very small spiniform tubuli. 
The cell-apertures are more or less floriform, and arranged in tolerably 
regular series; about twelve may be counted in the space of .J inch. 
A tangential section before me, shows several gradations between 
* By using this word without quotation marks I supposed that I would be understood 
to mean, simply vertical ridges, that were false, so far as they simulated either the true 
septa, or the **‘ pseudo-septa’’ of the Calenterata. 
1 
