64 
PALAEONTOLOGY OF NEW YORK. 
junction and on the same plane with the branches; five in the space of 
5 mm. Fenestrules oval, width generally about one-half the length. The 
specimens observed are without ornamentation. 
On the celluliferous face the branches are usually rounded, becoming 
angular or carinated where there are two ranges of apertures. Dissepi¬ 
ments rounded, depressed. The fenestrules appear narrower than on the 
opposite face, the width frequently being not more than one-fourth the 
length. Cell apertures minute, in two and three ranges, opening directly 
outward; twenty-five in the space of 5 mm.; sometimes nearly in contact, 
usually distant about one-half the diameter of an aperture: margins strong, 
elevated, decidedly indenting the borders of the fenestrules. 
Width of branch above a bifurcation, near the base of a bryozoum, 
.50 mm., increasing to nearly 1 mm. ; at some distance above the width is 
.30 mm., increasing to .60 or .70 mm.; width of dissepiments .30 mm.; 
length of fenestrules .70 mm. 
This species may be distinguished from F. (P.) obliqua, pi. xviii, figs. 8, 9, by 
its less robust appearance, the larger and more distant apertures, and the pres¬ 
ence of a carina between the ranges of cell apertures. 
Formation and, locality. In the lower Helderberg group, Catskill creek, N. Y. 
Fenestella (Polypora) obliqua, n. sp. 
PLATE XVIII, FIGS. 8, 9. 
In part Fenestella arta, Hall. Thirty-second Rept. N. Y. State Mus. Nat. Hist., p. 163. 1879. 
“ “ “ “ Report of State Geologist for 1882. Expl. pi. 18, figs. 4-9. 1883. 
Bryozoum infundibuliform, compact, undulating. Branches strong, angular, 
straight, sinuous or zigzag, according to the arrangement of the dissepi¬ 
ments. Bifurcations frequent. Dissepiments strong, angular; six in the 
space of 5 mm. Fenestrules elongate-oval. 
On the celluliferous face the fenestrules appear much narrower than on 
the opposite face, and the polyzoary presents a much more compact and 
rigid appearance. Cell apertures small, circular, in from two to four ranges; 
