CORALS AND BRYOZOA. 
163 
Fenestella (Polypora) porosa. 
PLATE XXXVIII, FIGS. 1-6. 
Fenestella porosa, Halt,. Trans. Albany Institute, vol. x, abstract, p. 26. 1881. 
“ ( Polypora) porosa, Hall. Report of State Geologist for 1882. Expl. pi. 31, figs. 1-6. 1883. 
Bryozoum infundibuliform, fronds large, somewhat rigid in appearance, rapidly 
expanding. Branches moderately strong, width above a bifurcation .33 mm., 
increasing to .70 mm., angular, slightly carinated. Interstices slightly nar¬ 
rower than the wider portion of the branches. Dissepiments comparatively 
strong, width .33 mm., angular, slightly carinated, on the. same plane with 
the branches, four in the space of 5 mm. Fenestrules regularly oval, height 
.60 mm., width usually about .40 mm. 
On the celluliferous face the branches are rounded. Dissepiments angular, 
carinated, slightly depressed. Fenestrules much narrower than on the 
opposite face, length from two to three times the width. Cell apertures in 
three and four ranges, sixteen in the space of 5 mm., separated by a little 
more than the diameter of an aperture. 
This species may be distinguished from F. (P.) hexagonalis, by the smaller 
size and closer arrangement of branches and dissepiments; from F. (P.) nexa 
and F. (P.) mutabilis by the stronger and more compact appearance of the frond 
and absence of ridges separating the ranges of apertures. 
Formation and locality. Upper Helderberg group, Walpole, Ontario, Canada. 
Fenestella (Polypora) perundata. 
PLATE XXXVIII, FIGS. 7-13. 
Fenestella perundata, Hall. Trans. Albany Institute, vol. x, abstract, p. 27. 18S1. 
( Polypora ) perundata, Hall. Report of State Geologist for 1882. Expl. pi. 31, figs. 7-13. 1883. 
Bryozoum infundibuliform, fronds large, with frequent, strong, radial folds or 
undulations. Branches strong, width above a bifurcation .60 mm., increasing 
to 1 mm., angular or with a slight carina, anastomosing, sinuous or zig-zag, 
irregular, the face often presenting a reticulated appearance. Interstices 
