60 
PALEONTOLOGY OF NEW YORK. 
circular, in two and three ranges, opening directly outward, eighteen or twenty 
in the space of 5 mm., separated by less than the diameter of an aperture. 
Three ranges of apertures usually occur, only for 1 or 2 mm. on the branch 
before bifurcating, but sometimes the intermediate range extends for 4 or 
5 mm.: margins elevated, indenting the borders of the fenestrules. Branch 
with a very slight carina between the ranges of cell apertures. 
This species is distinguished by its closely arranged, sub-parallel branches, 
distant bifurcations, and its rigid appearance. 
Formation and locality. Lower Helderberg group, near Clarksville, N. Y. 
Fenestella (Polypora) Idothea. 
PLATE XIX, FIGS. 14, 15. 
Polypora elegans? Hall. Twenty-sixth Rept. N. Y. State Mus. Nat. Hist., p. 97. 1874. 
Fenestella Idotliea, “ Thirty-second Rept. N. Y. State Mus. Nat. Hist., p. 166. 1879. 
“ “ “ Report of State Geologist for 18S2. Expl. pi. 19, tigs. 14, 15. 1S83. 
Bryozoum observed only as flattened fragments, the form of a perfect specimen 
is, therefore, not definitely known. Branches moderately slender, rounded 
on the non-celluliferous side, and marked by fine striae. Bifurcations fre¬ 
quent. Width of interstices greater than that of the branches. Dissepi¬ 
ments slender, rounded, six in the space of 5 mm., expanded at their junction, 
and on the same plane as the branches. Fenestrules sub-quadrangular, longer 
than wide. 
On the celluliferous face the branches are angular or sub-angular, appear¬ 
ing stronger than on the opposite face. Dissepiments rounded, sometimes 
angular and depressed. Cell apertures oval, in two and three ranges, open¬ 
ing laterally, length nearly twice the width, and separated by a space equal 
to one-half the length of an aperture, from eighteen to twenty-two in the 
space of 5 mm.: margins slightly elevated, not indenting the borders of the 
fenestrules Between the ranges of apertures, the branch is rounded or 
sub-angular, and marked by very fine tortuous strife. 
Width of branch above a bifurcation .25 mm., increasing to .40 mm.; 
diameter of dissepiments .20 mm.; length of fenestrules from .40 to .60 mm.; 
width from .30 to .40 mm. 
