86 Cincinnati Society of Natural History. 
or less inosculated loose masses, several inches in diameter, consisting of 
convoluted fronds, varying in thickness from .15 inch, to.3 inch. This 
irregularity of growth, which is very characteristic of the species, is 
caused by the frequent elevation of the face of a frond into a secondary 
frondescent growth, which eventually anastomoses with other similar 
divisions of the zoarium. The surface is sometimes nearly smooth, 
but usually is studded with small, rounded or conical monticules, the 
summits of which are subsolid, each being occupied by a small “macula” 
of interstitial cells. The arrangement of the monticules and maculae, 
in conformity with that of the cells, is very regular. Measuring from 
center to center, seven may be counted in the space of .5 inch. The 
cell-apertures are circular, and regularly arranged in decussating 
series, which are more or less curved around the monticules. One or 
two rows of cellsimmediately surrounding each of the small ‘‘ macule,” 
are conspicuously larger than the ordinary cells, their apertures having 
a diameter varying from 1-150th to 1-100th of an inch, while the 
diameter of the cell-apertures in the interspaces is about 1-200th of an 
inch. Measuring along one of the series, twelve cells may be counted 
in the length of .1 inch. On an example of this species the cell-inter- 
spaces are comparatively thick, and may show, according to the stage of 
development and state of preservation, either all, or one or two, of 
three different appearances. In the first (probably due to attrition ), 
the interspaces are smooth and apparently solid. In the second, they 
carry numerous small pits, representing the orifices of the interstitial 
cells. In the third (Pl. L, fig. 2), the apertures of the interstitial cells 
are obscured by an exceedingly large number of small spines or 
granules. The last phase doubtlessly represents the zoarium in its 
perfect and fully matured stage. 
Tangential sections, according to the depth at which the zoarium is 
divided, may show one or both of two distinct phases. In the first 
(the one usually. obtained on account of the unusual brevity of the 
“matured” portion of the tubes) the cells have moderately thin walls, 
are subangular or nearly circular, and in contact at limited points, the 
intervening spaces being occupied by smaller and angular interstitial 
cells. The spiniform tubuli, if any at all can be detected, are small and 
inconspicuous. In the second phase, which is obtained by cutting the 
cells of a fully matured specimen just below the surface, the intersti- 
tial cells appear to be almost entirely suppressed by the remarkably 
great development of spiniform tubuli, which are ranged in one or 
two closely crowded series around the cell cavities. Fig. 2a, Pl. I., 
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