CORALS AND BRYOZOA. 
167 
in two and three ranges, seventeen in the space of 5 mm , separated by a 
little less than the diameter of an aperture. 
This species may be distinguished from others, having branches and dissepi¬ 
ments of about the same size, by its irregular growth and the prominent 
striations on the branches of a portion of the frond. 
Formation and locality . Upper Helderberg group, Walpole, Ontario, Canada. 
Fenestllla (Polypora) submutans. 
PLATE XL, FIGS. 3-5. 
Fenestella submutans, Hall. Trans. Albany Institute, vol. x, abstract, p. 21. 1881. 
“ ( Polypora) submutans. Hall. Report of State Geologist for 1885, advance sheets. Expl. pi. 40, 
figs. 3-5. 1886. 
Bryozoum infundibuliform. Branches moderately strong, width above a bifur¬ 
cation .33 mm., increasing to .60 mm., somewhat irregular, rounded or sub- 
angular, sometimes slightly carinated. Interstices narrower than the 
branches. Dissepiments comparatively strong, width .35 mm., sometimes 
oblique to the branch, rounded or sub-angular, occasionally slightly carinated, 
on a plane with the branches, occurring at irregular intervals. Fenestrules 
variable in form, sub-oval, immediately above a bifurcation lanceolate, length 
about 1 mm., width from .25 to .50 mm. 
On the celluliferous face the branches are rounded. Dissepiments rounded, 
a little depressed. Fenestrules slightly narrower than on the opposite face. 
Cell apertures in from three to five ranges, opening outward and laterally, 
eighteen in the space of 5 mm., separated by less than the diameter of an 
aperture; margins distinctly elevated, strongly indenting the borders of the 
fenestrules and visible from the opposite face of the frond. Ranges of aper¬ 
tures separated by low, rounded ridges; the ridges and surface between aper¬ 
tures with numerous, small, conical nodes. 
This species most' nearly resembles F. (P.) aculeata , but the frond is more 
irregular, the branches more slender, and the fenestrules more elongate. 
Formation and locality. Upper Helderberg group, Falls of the Ohio river. 
