CORALS AND BRYOZOA. 
139 
the appearance of being composed of oblique, imbricating, walled cells. Fre¬ 
quently the frond is broken in such a manner, that the under side of the 
carin* and seal* are shown, when they present precisely the same appear¬ 
ance as the non-celluliferous face of some frond of a species having very 
slender, angular branches, strong, rounded dissepiments and nearly circular 
fenestrules. 
The character of the seal* separates this species from all others of this for¬ 
mation, except F. ( IJ.) pernodosa and F. (JJ) elegantissima; from the former of 
which it is distinguished by the more regular branches, narrower, more rounded 
dissepiments and the lines of nodes on the branches; from the latter, by the 
more slender branches and dissepiments, smaller fenestrules and the ornamenta¬ 
tion of the branches. 
Formation and locality. Upper Helderberg group, Walpole, Ontario, Canada. 
Fenestella (Unitrypa) pernodosa. 
PLATE UK, FIGS. 1-11. 
Fenestella ( Hemitrypa ) pernodosa. Hall. Trans. Albany Institute, vol. x, abstract, p. 35. 1881. 
“ ( Unitrypa) “ “ Report of State Geologist for 1885, advance sheets. Expl. pi. 
53, tigs. 1-11. 1S86. 
Bryozoum infundibuliform, fronds large. Branches slender, width above a bi¬ 
furcation about .30 mm., scarcely increasing in size until just before bifur¬ 
cating, when the width is from .50 to .60 mm., sub-parallel, rounded or 
sub-angular, ornamented with prominent nodes, irregularly disposed, but 
usually at varying distances along the middle of the branch. Interstices a 
little wider than the branches. Dissepiments strong, width .75 mm., flattened 
or gently rounded, a little depressed, occasionally nodose; when the dissepi¬ 
ments of a branch are opposite to each other the branch has the appearance 
of a slight ridge crossing the dissepiments. Fenestrules oval, length .90 mm., 
width about .45 mm. 
On the celluliferous face the branches appear stronger, usually sinuous. 
Dissepiments rounded, much depressed. Fenestrules narrower than on the 
opposite face. Cell apertures in two ranges, opening nearly directly outward, 
