112 
PALAEONTOLOGY OF NEW YORK. 
strongly indenting the borders of the fenestrules. Surface between ranges 
of apertures angular, nodose. 
This species may be distinguished by the depressed dissepiments on both faces 
of the frond. 
Formation and locality. Upper Helderberg group, Falls of the Ohio river. 
Fenestella .equalis. 
PLATE XLVI, FIGS. 27-31. 
Fenestella (Squalls, Hall. Trans. Albany Institute, vol. x, abstract, p. 31. 1881. 
Bryozoum infundibuliform. Branches moderately slender, width above a bifur¬ 
cation .30 mm,, increasing to .50 mm., very gradually enlarging, rigid, 
angular, slightly carinated. Nearly all the specimens observed are par¬ 
tially covered by the original rock deposit, leaving only the summits of the 
branches exposed, giving them a very slender appearance ; width not more 
than .20 mm.; bifurcations distant. Interstices nearly twice as wide as the 
branches. Dissepiments comparatively strong, width .30 mm., angular, 
slightly carinated, on a plane with the branches, live in the space of 5 mm. 
Fenestrules sub-quadrangular, length 70 mm., width about .50 mm. 
On the celluliferous face the branches are angular. Dissepiments angular, 
much depressed. Fenestrules smaller and more oval than on the opposite 
face. Cell apertures in two ranges, eighteen in the space of 5 mm., separated 
less than the diameter of an aperture: margins thin, slightly elevated. Sur¬ 
face slightly carinated and with prominent conical nodes which usually occur 
opposite a dissepiment, but frequently on other portions of the frond. 
This species may be distinguished by the rigid branches, sub-quadrangular 
fenestrules, strong dissepiments, and the prominent nodes opposite dissepiments 
on the celluliferous face. 
Formation and locality. Upper Helderberg group, Falls of the Ohio river. 
