CORALS AND BRYOZOA. 
51 
when the dissepiments are opposite, becoming more or less sinuous or zigzag 
when the dissepiments alternate. Bifurcations frequent. Interstices nar¬ 
rower than the branches. Dissepiments strong, angular, seven or eight in 
the space of 5 mm., on.the same plane, or slightly elevated above the branches, 
sometimes continuing across the branches, uniting with other dissepiments 
forming a continuous irregular elevation, which is more prominent than the 
branches. Fenestrules broadly oval, sometimes nearly circular. 
On the celluliferous face the branches are broadly angular and the dissepi¬ 
ments rounded and much depressed. The fenestrules appear narrower than 
on the opposite face. Cell apertures in two ranges, opening directly out¬ 
ward, twenty in the space of 5 mm., distant a little more than the diameter 
of an aperture: margins elevated, not indenting the borders of the fenes¬ 
trules. Branches with comparatively strong caringe having a height of .10 
mm., slightly expanded along the summits. 
Width of branch above a bifurcation .25 mm., increasing to .50 mm. ; 
diameter of dissepiments .33 mm.; fenestrules .38 mm. long. 
This species on the non-celluliferous face resembles F. Coronis, but is dis¬ 
tinguished by its more compact growth, slender branches and oval fenestrules. 
Formation and locality. Lower Helderberg group, near Clarksville, N. Y. 
Fenestella Coronis. 
PLATE XXI, FIGS. 10-13. 
Fenestella Coronis, Hall. Thirty-second Rept. N. Y. State Mus. Nat. Hist., p. 171. 1879. 
“ “ “ Report of State Geologist for 18S2. Expl. pi. 21, figs. 10-13. 1883. 
Bryozoum infundibuliform, radially undulating. Branches strong, angular or 
rounded on the non-celluliferous side, and flattened for a short distance below 
the bifurcation. Dissepiments strong, angular, slightly expanded at their 
junction, and on the same plane with the branches. Fenestrules oval or 
quadrangular, varying in size and form, and generally wider than the 
branches. 
On the celluliferous face, the branches and dissepiments are angular, and 
the latter much depressed. The fenestrules appear narrower than on the 
