158 PALEONTOLOGY 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 the 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 XXXVl, FIGS. 23, M ; AND PLATE XL, FIGS. 1,2. 



Fenestella quadrangtilarix, Hall. Trans. Albany Institute, vol. x, abstract, p. 21. 1881. 



" {Polypora) quadrangularis, Hall. Report of State Geologist for 1882. Expl. pi. 28, figs. 8-13 ; 



pi. 29, figs. 23, 24. 1883. 

 «« " " " Report of State Geologist for 1885, advance sheets. Expl. pi. 



40, figs. 1, 2. 1886. 



BRrozouM 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- 



