266 Cincinnati Society of Natural History. 
elevated into a radially divided monticule. The true cells are best 
developed in the inter-monticular spaces, where they are more or less 
isolated by interstitial cells, the mouths of which are, however, closed 
at the surface; in consequence, the interstitial spaces and “ macule”’ 
appear to be solid. In sections, the axial region is seen to be occupied 
only by the true zoccial tubes; here they are polygonal, with very 
_ thin walls, and few or no diaphragms. As they approach the surface 
their walls are slightly thickened, and a large number of thin-walled 
interstitial tubes are abruptly developed.. These sometimes have 
flexuous walls, and are divided by a large number of horizontal 
diaphragms, which, especially just beneath the surface of fully 
matured examples, are closely crowded, and placed upon the same 
level in contiguous tubes. Small spiniform tubuli are numerous, but 
only in fully matured zoaria. 
Type, Constellaria florida, Ulrich, from the Cincinnati group. 
A comparison between the foregoing descriptions will show the 
grounds upon which I propose to separate Constellaria from Stellipora. 
The rule, among both American and European paleontologists, has 
been to regard these two really distinct genera as synonymous, and, 
with scarcely a single exception, all drew their diagnosis of Séellipora, 
from Cincinnati examples of what I now call Constellaria florida, 
doubtlessly supposing them, as I did, to be identical with Stedlé- 
pora antheloidea, Hall. That this supposition was erroneous, any 
one might have detected, by comparing the specimens with Hall’s 
description of that genus and species. He distinctly says, that the 
zoarium consists of an expanded crust, “apparently attached to some 
other marine body.” He says further, that the spaces between the 
elevated stars are “almost smooth, or finely granulated.” Now, the 
zoarium of C. florida is never thinly expanded, and parasitically 
attached to foreign objects, but consists of erect flattened branches, 
‘that are as truly free as any other ramose form. The inter-monticular 
Spaces too are never smooth or finely granulated (that is, solely 
occupied by closed interstitial cells), but are occupied by a large 
number of uniformly distributed true zocecial apertures. These 
important differences, if they had not shown the observer that the 
Cincinnati specimens were generically distinct from the New York 
Trenton species, he would at least have seen the necessity for a 
specific separation. From an examination of their internal structure, 
it becomes evident that they are distinguished by another difference 
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