148 Cincinnati Society of Natural History. 
AMERICAN PALHAOZOIC BRYOZA. 
By kh. 70. Uimicr, 
[Continued from Vol. 6., p. 92. | 
DEKAYIA, Edwards and Haime. 
This genus, founded by the eminent French authors, Milne Edwards 
and Jules Haime, upon their Cincinnati group species, D. aspera, is in 
many respects related to Heterotrypa, Nicholson, and Dekayelia, 
Ulrich. In the remarks appended to my descriptions of the latter 
genera, I have already shown the points of difference in their structure. 
It is therefore quite superfluous to again discuss the generic affinities 
of Dekayia, but the following brief description of the genus, based 
upon the aggregate of characters presented by six different Trenton 
and Cincinnati Group species, is, I believe, of more value. 
Zoarium growing upward from a more or less largely expanded 
basal attachment, into, rarely cylindrical, usually flattened branches, 
which occasionally may become sub-froudescent. Surface sometimes 
with low monticules, usually, however, nearly even. Cells with 
polygonal apertures, sometimes apparently consisting of one kind 
only, but more commonly a few interstitial cells may be detected, 
which are more especially developed between the individuals con- 
stituting the groups of larger cells, that always furnish a more or less 
conspicuous feature of the surface. Cell-walls always thin, sometimes 
excessively so, there being but one species (D. trentonensis, n. sp.) 
in which the tube-walls, as the tubes pass from the axial into the 
peripheral region, are more than only very slightly thickened. Spini- 
form tubuli in the typical species few, but very large, and not in- 
frequently already present in the axial region of the zoarium. In 
other species (D. appressa, n. sp., and D. paupera, n. sp.) *they are 
reduced in size, but their number remains about the same. In one 
(D. multispinosa, n. sp.), they are also comparatively small, but more 
numerous. When in good state of preservation, at certain stages in the 
crowth of the zoarium, the cell-apertures over larger or smaller patches 
of the surface are covered by a thin calcareous pellicle. On such 
covered spots the spiniform tubuli are very conspicuous. Diaphragms 
straight, usually few, sometimes almost entirely absent, occasionally 
(in the peripheral region) from one half to one tube-diameter distant 
from each other. 
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