American Paleozoic Bryozoa. 151 
lated diaphragm, these structures becoming however more numerous 
in the peripheral region, where they cross the tubes at distances apart 
of from one half to one tube diameter. The cells turn very abruptly 
from the axial into the peripheral region, becoming at the same time 
slightly thickened, and proceeding in their course to the surface they 
follow a line drawn at a right angle to the longitudinal axis of the 
branch. In the peripheral region may be noticed quite a number of 
small, obscurely beaded tubes, in which the diaphragms are somewhat 
more closely set than in the proper zoccia, and always cross the tube 
at the periodic points of stricture. In other tubes again the dlia- 
phragms are remote and sometimes entirely wanting. On the whole 
the tabulation of this species is peculiar. The spiniform tubuli are 
always distinctly visible, and have the usual structure. 
Tangential sections show that the cells are thin-walled, and more or 
less angular, that the spiniform tubuli are comparatively small, and oc- 
cupy the angle of junction between every three or four cells, and that 
they are further isolated by being situated between two to four small 
interstitial cells. From five to fifteen of the latter also occupy the in- 
terstices between the larger cells of the clusters, which even in these 
sections are not very striking. 
This species is distinguished from D, aspera externally by its more 
regularly dendroidal growth, smooth surface (so far as monticules are 
concerned), and less conspicuous spiniform tubuli. Internally the 
much more numerous diaphragms, and interstitial tubes, beside the 
smaller spiniform tubuli present weighty points of difference. 
Formation and locality: Cincinnati group. Rather rare on the hills 
back of Cincinnati, O., and Covington, Ky., at an elevation of from 300 
to 350 feet above low water mark in the Ohio river. 
DEKAYIA TRENTONENSIS, n. sp. (PI. VI., figs. 6 and 6a.) 
Zoarium dendroid, branches slightly compressed, frequently divid- 
ing, and from .15 inch (terminal ends) to .4 of an inch (primary 
branches) in diameter. Entire height of zoarium probably not more 
than two and one half inches. Surface with low and rounded monti- 
cules, of which five may be counted in .5 inch. They are occupied by 
clusters of cells a little larger than those in the intermediate spaces ; 
occasionally a few small, perhaps interstitial, cells occupy the summit. 
Cells with comparatively thick walls, and a diameter of about ;1,th 
of an inch, while the diameter of those in the clusters mentioned does 
not exceed 4th of an inch. The large spiniform tubuli are qmite 
prominent and easily recognized. 
