150 
PALAEONTOLOGY OF NEW YORK. 
This species may be distinguished from F. (II.) columellata, by the more 
distant branches and dissepiments, and consequent larger fenestrates, there 
being only nine dissepiments in the same space occupied by fourteen in that 
species; from F. (H.) favosa , by the much wider dissepiments and their greater 
distance, the dissepiments of that species being very slender ; from F. (H.) nana, 
by the same characters that distinguish it from F. (II.) columellata ; from F. 
(II.) cribrosa, by the wider and more distant dissepiments; from all the species 
at present known it is generally distinguishable by the much coarser appear¬ 
ance of the frond. 
Formation and locality. Upper Helderberg group, Walpole, Ontario, Canada. 
POLYPORA, McCoy. 1845. 
B. Species having more than two ranges of cell apertures on the branch. 
a. Forms having two and three ranges of cell apertures. 
Fenestella (Polypora) celsipora. 
PLATE XLI, FIGS 10-22 ; AND PLATE XLII, FIG. 5-10. 
Fenestella celsipora, Hall. Trans. Albany Institute, vol. x, abstract, p. 24. 18S1. 
“ ( Polypora ) celsipora? Hall. Report of State Geologist for 1882. Expl. pi. 33, figs. 5-8. 1883. 
“ “ “ ? “ Report of State Geologist for 18S2. Expl. pi. 33, figs. 9, 10. 1883. 
“ “ “ “ Report of the State Geologist for 1885, advance sheets. Expl. pi. 41, 
figs. 16-22. 1886. 
Bryozoum infundibuliform, fronds large, with frequent, strong, radial undula¬ 
tions. Branches moderately- slender, very gradually increasing in size, 
rounded or sub-angular, occasionally granulose; width above a bifurcation 
.25 to .30 mm., increasing to .50 or .60 mm., bifurcations at intervals 
of from 15 to 40 mm. Interstices usually wider than the branches, some¬ 
times twice the width. Dissepiments comparatively strong, width varying 
from .33 to .50 mm., rounded, granulose, five in the space of 5 mm., on 
the same plane with the branches and expanded at their junction. Fenes¬ 
trates variable in size, broadly oval or sub-quadrangular, width from two- 
thirds to three-fourths the length, sometimes the two dimensions are nearly 
or quite equal. 
On the celluliferous face the branches are sub-angular. Dissepiments 
slender, depressed. Fenestrates much narrower than on the opposite face. 
