r 



CORALS AND BRYOZOA. 163 



Fenestella (Poltpora) porosa. 



PLATE XXXVin, FIGS. 1-6. 



Fenestella porosa. Hall. 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-ls. 



FenegUlla peruiideUa, Hall. Trans. Albany Institute, vol. x, abstract, p. 27. 1881. 



" (Poiypora) 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 



