I 



CORALS AND BRYOZOA. 167 



in two and three ranges, seventeen in the space of 5 mm , separated by a 

 little less than the diameter of an aperture. 



This species may be distinguished from others, having branches and dissepi- 

 ments of about the same size, by its irregular growth and the prominent 

 striations on the branches of a portion of the frond. 



Formation and locality. Upper Helderberg group, Walpole, Ontario, Canada, 



Fenestllla (Polypora) submutans. 



PLATE XL, FIGS. 3-6. 



Fenettella submutans, Hali,. Trans. Albany Institute, vol. x, abstract, p. 21. 1881. 



" (Polypora) submutans. Hall. Report of State Geologist for 1885, advance sheets. Expl. pi. 40, 



fife's. 3-5. 1886. 



Bbyozoum infundibuliform. Branches moderately strong, width above a bifur- 

 cation .33 mm., increasing to .60 mm., somewhat irregular, rounded or sub- 

 angular, sometimes slightly carinated. Interstices narrower than the 

 branches. Dissepiments comparatively strong, width .35 mm., sometimes 

 oblique to the branch, rounded or sub-angular, occasionally slightly carinated, 

 on a plane with the branches, occurring at irregular intervals. Fenestrules 

 variable in form, sub-oval, immediately above a bifurcation lanceolate, length 

 about 1 mm., width from .25 to .50 mm. 



On the celluliferous face the branches are rounded. Dissepiments rounded, 

 a little depressed. Fenestrules slightly narrower than on the opposite face. 

 Cell apertures in from three to five ranges, opening outward and laterally, 

 eighteen in the space of 5 mm., separated by less than the diameter of an 

 aperture ; margins distinctly elevated, strongly indenting the borders of the 

 fenestrules and visible from the opposite face of the frond. Ranges of aper- 

 tures separated by low, rounded ridges ; the ridges and surface between aper- 

 tures with numerous, small, conical nodes. 



This species most nearly resembles F. (P.) aculeata, but the frond is more 

 irregular, the branches more slender, and the fenestrules more elongate. 

 Formation and localliy. Upper Helderberg group, Falls of the Ohio river. 



