158 
PALAEONTOLOGY OF NEW YORK. 
.33 mm., gradually increasing to .50 mm.; near the base stronger, rounded, 
with numerous strong, conical, irregularly disposed nodes; bifurcations 
at intervals of from 6 to 15 mm. Interstices of about the same width 
as the branches. Dissepiments comparatively strong, width from .40 to .50 
mm., rounded, smooth, five in the space of 5 mm., on the same plane with 
the branches, .slightly expanded at their junction. Fenestrules oval, width 
equal to one-half the length. 
On the celluliferous face the branches are angular, becoming rounded 
below a bifurcation. Dissepiments angular depressed. Fenestrules slightly 
narrower than on the opposite face. Cell apertures in from two to four 
ranges, fifteen in the space of 5 mm., separated by less than tlie diameter 
of an aperture; ranges of apertures separated by ridges with numerous, 
prominent, conical nodes. 
This species may be easily distinguished by the prominent nodes and the 
longitudinal ridges separating the rows of apertures. 
Formation and locality. Upper Helderberg group, Falls of the Ohio river. 
Fenestella (Polypora) quadrangularis. 
PLATE XXXV, FIGS. 8-13; PLATE XXXVI, FIGS. 23,21; AND PLATE XL, FIGS. 1,2. 
Fenestella quadrangularis. Hall. Trans. Albany Institute, vol. x, abstract, p. 21. 1881. 
“ ( Pultjpura ) quadrangularis, Hall. Report of State Geologist for 1882. Expl. pi. 28, figs. 8-13 ; 
pi. 29. fig-s. 23, 24. 1883. 
“ “ “ “ Report of State Geologist for 1S85, advance sheets. Expl. pi. 
40, figs. 1, 2. 1886. 
Bryozoum infundibuliform. Branches strong, width above a bifurcation .50 
increasing to 1 mm., angular, carinated ; carina broad, angular, with promi¬ 
nent, conical nodes, which usually occur opposite dissepiments, but are 
sometimes irregularly disposed; bifurcations at intervals of from 8 to 
15 mm. Interstices narrower than the branches, sometimes less than half 
the width. Dissepiments strong, width .50 to .60 mm., angular, carinated, 
slightly depressed below the plane of the branches, five in the space of 5 mm. 
Fenestrules regularly oval, width equal to two-thirds the length. 
On the celluliferous face the branches are rounded. Dissepiments rounded, 
depressed. Fenestrules of the same size as on the opposite face. Cell aper- 
