American Paleozoic Bryozoa. 153 
they are not readily detected. Cells thin-walled, and with the excep- 
tion of the groups mentioned, in all probability consist of one kind only, 
those of the ordinary size having a diameter of =4,th inch, while that 
of those in the clusters may exceed ,,th inch. An occasional small 
cell is met with, that, though I much doubt it, may be of the nature of 
an interstitial cell. 
Longitudinal sections show that the tubes in the axial region are 
nearly vertical, and that in their course to the surface they bend ab- 
ruptly outward, their walls, which, as usual, are very thin in the axial 
region, becoming but slightly thickened as they enter the peripheral 
portion. Diaphragms are but rarely developed in the “immature,” or 
axial region, and only from five te ten in the “matured” portion of a 
tube, where they are placed at distances apart of from one half to one 
tube-diameter. Occasionally a small and short tube may be detected 
in which the diaphragms appear to be a little more closely set than is 
the case in the ordinary tubes. The spiniform tubuli being few and 
of rather small size, are not a conspicuous feature in sections of this 
kind. 
In tangential sections the cells are thin-walled and angular, the 
groups of larger ones being often very distinct (see fig. 7b, Pl. VI.) 
On account of the thin cell-walls the spiniform tubuli, though of com- 
paratively small size, are very apparent, occupying the angles of 
junction of every three, four or five cells. 
The frequently branching, sometimes anastomosing zoarium of this 
species, does not resemble very closely any associate form. Some of 
the smaller specimens of Dekayella ulrichi, Nicholson sp., occurring 
over two hundred feet lower in the series, bear some external resem- - 
blance to fragments of D. appressa. The numerous interstitial tubes, 
and rounded cell-apertures of the former, amply serve the purpose of 
distinguishing them. 
Formation and locality: Cincinnati group, at Cincinnati, Ohio. 
Rather common at an elevation of about 425 feet above the Ohio 
river. Its vertical range is restricted to only a few feet. 
DEKAYIA PAUPERA, n. sp. (PI. VI, figs. 10 and 10a.) 
Zoarium ramose, the more or less flattened branches growing up- 
ward from a large and thinly expanded base, to a height of one and 
one half inches or a little more; varying in thickness from .15 to .3 of 
an inch, andin width from .2 to .8 of an inch. Surface without 
monticules. Cells polygonal, with excessively thin walls, the ordinary 
