CORALS AND BRYOZOA. 
117 
branches; about six in the space of 5 mm. Fenestrules oval or sub-quad¬ 
rangular, length 1.40 mm., width from .50 to .60 mm. The celluliferous face 
has not been observed. 
This species may be distinguished by the comparatively slender branches, 
with frequent, prominent, conical nodes, and the large fenestrules. It most 
nearly resembles F. proceritas, but the branches are stronger and the fenestrules 
larger. 
Formation and locality. Upper Helderberg group, Ontario, Canada. 
Fenestella clathrata, n. sp. 
(not figured.) 
Bryozoum infundibuliform. Branches moderately slender, width above a bifur¬ 
cation .35 mm., increasing to .50 or .60 mm., sometimes more, angular and 
slightly carinated, very gradually enlarging, increase in width scarcely per¬ 
ceptible, sinuous or zig-zag, anastomosing or connected by very short dissepi¬ 
ments ; bifurcations infrequent. Interstices of about the same width as the 
branches. Dissepiments strong, width .66 mm., angular, slightly carinated, 
the carinse connecting with those of the branches and on the same plane; 
when the branches anastomose the portions so connected have the same width 
as the dissepiments; the carinae of adjacent branches unite and at their 
junction have a small conical node, four in the space of 5 mm. Fenestrules 
broadly oval, frequently nearly circular, length .55 mm. 
On the celluliferous face the branches are sinuous. Dissepiments rounded, 
slightly depressed. Fenestrules a little narrower than on the opposite face. 
Cell apertures in two ranges, opening directly outward, twenty in the space 
of 5 mm., separated by less than the diameter of an aperture: margins very 
distinctly elevated, but not indenting the border of the fenestrules. Surface 
between ranges of apertures carinated; carinae moderately thick, slightly 
elevated. 
This species is similar in general appearance to F. erectipora, but may be dis¬ 
tinguished by its smaller, more closely arranged branches and more closely 
