286 
PALEONTOLOGY OF NEW YORK. 
FENESTRAPORA, Hall. 1884. 
Fenestrapora biperforata. 
PLATE LXVI, FIGS. 31-39. 
Fenestrapora bi.perforafa. , Hall. Report of State Geologist for 1SS4, pi. 2, fig-. 17. 18s5. 
Bryozoum infundibuliform; branches moderately slender, width above a bifur¬ 
cation from .20 to .30 mm., increasing to .45 or .50 mm., straight, sinuous or 
zig-zag, according to the position of the dissepiments; narrower portions of 
the branches rounded or sub-angular, becoming flattened as they approach a 
bifurcation; sometimes there is a strong striation along the middle of the flat¬ 
tened branch, having the appearance of a carina; at other times there are irregu¬ 
larly disposed, short, interrupted striations and frequently the branch is marked 
by numerous, comparatively strong granules or small nodes; there are also 
pores or perforations, irregularly disposed and greatly varying in number in 
different fronds, often numerous, sometimes oval, length .30 mm., width one- 
third the length, without peristomes ; at other times these pores are elongate- 
triangular, the upper portion strongly elevated; these pores sometimes occur 
on the dissepiments, and altogether they frequently form the most conspic¬ 
uous feature of this face of the frond. Interstices wider than the branches. 
Dissepiments strong, width from .30 to .40 mm., and occasionally even more, 
flattened or rounded, on a plane with the branches and expanded at their 
junction, five in the space of 5 mm. Fenestrules oval, length generally from 
.60 to .70 mm., width from one-half to two-thirds the length. 
On the celluliferous face the branches are angular. Dissepiments rounded, 
much depressed. Fenestrules narrower than on the opposite face. Cell 
apertures in two ranges, sometimes slightly oblique to the axis of the branch, 
opening almost directly outward, eighteen in the space of 5 mm., separated by 
less than the diameter of an aperture. Peristomes strong, distinctly elevated, 
indenting the borders of the fenestrules. Surface between the ranges of 
apertures carinated; carina about .25 mm. in height, for about one-half that 
distance very thin, then rapidly expanding to a width of .10 or .12 mm., the 
summit usually flat, and with a row of oval pores, which are frequently 
