264 Cincinnati Society of Natural History. 
central space ; these occasionally are divided at the outer wide end, or 
more commonly, have a few shorter rays intercalated between them: 
The stars are of circutar or elliptical shape, and occur at rather un- 
equal intervals, being often almost in contact on one side, and separated 
on another side by a distance nearly equaling their diameter. The 
true zocecia are entirely restricted to the elevated ridges of the stars 
when they are in close contact, They have subcircular apertures, the 
diameter of which averages about ;+.th of an inch. All the depressed 
portions of the star-shaped monticules, and the spaces left between 
them, are solely occupied by interstitial cells, the mouths of which are, 
so far as known, invariably covered by a faintly pitted, sometimes 
apparently granulose, interstitial membrane. 
Tangential sections (Pl. XIV., fig. 1) show that the true cells are 
ageregated into irregularly wedge-shaped converging groups, that they 
have a subcirculay form, and moderately thick walls, and that they 
never occur in the inter-monticular spaces, which, like the depressed 
rays and central area of the monticules or stars. are solely occupied 
by interstitial cells. These, though of very unequal dimensions, are 
always smaller than the true cells, from which they are further 
distinguished by being polygonal, and very thin walled. Often a few 
of these small cells are wedged in between the true zoecia. 
Longitudinal sections (Pl. XIV., fig. la) usually show only a very 
limited number of the true zocecia, which, when the section passes 
through any, are distinguishable by their somewhat larger size, thicker 
walls, and very few horizontal diaphragms. All the tubes proceed 
more or less abruptly from the wavy epithecal line, to the surface, those 
of the smaller or interstitial set, being sometimes apparently per- 
pendicular throughout, and without any prostrate portion whatever. I 
have also noticed a few instances in which but little separated tubes 
were inclined in opposite directions. The diaphragms in the interstitial 
tubes are developed at diminishing intervals, the shortest observed 
equaling about one third of a tube diameter. | 
In my scheme of classification, I placed Constellaria, Dana, as a sub- 
genus under Stellipora, Hall. This was, I now think, an error, and I 
propose hereafter to regard Constellaria as entitled to rank as a dis- 
tinct. genus. Iam led to this conclusion by a critical comparison be- 
tween the two species upon which the names were founded. The one, 
Stellipora antheloidea, I have just described, while of the other, I pub- 
lished a partial description in a preceding number of this JoURNAL, 
