1G8 PALjEONTOLOGY OF NEW YORK. 



Fenestella (Polypora) brevisulcata. 



PLATE XL. FIGS. 12-16. 



F^negUUa bmUvicata, Hall. Trans. Albany Institute, vol. x, abstract, p. 26. 1881. 



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



12-15. 1886. 



Bryozodm infundibuliform, fronds large. Branches moderately slender, width 

 above a bifurcation .33 mm., increasing to .66 mm., angular or sub-angular, 

 becoming flattened, and concave immediately below a bifurcation, with a 

 row of small nodes at irregular intervals, along the middle of the branch, 

 which is occasionally carinated ; bifurcations distant. Interstices wider than 

 the branches. Dissepiments comparatively strong, width .30 mm., rounded, 

 very slightly depressed below the plane of the branches, five in the space of 

 9 mm. Fenestrules oval, length about 1.25 mm., width from .40 to .60 mm. 

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

 depressed. Fenestrules of the same size as on the opposite face. Cell aper- 

 tures in three and four ranges, sixteen in the space of 5 mm., separated by 

 less than the diameter of an aperture. 



This species may be distinguished by its angular branches, which become 

 flattened as they increase in size and have a depression along the middle, 

 immediately below a bifurcation. 



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



Fenestella (Polypora) stbiatopora. 



PLATE XL, FIGS. 16-19. 



Fmeatella striatopora, Hall. Trans. Albany Institute, vol. x, abstract, p. 2H. 1881. 



" {Polypora) striatopora. Hall. Report of State Geologist for 188.5, advance sheets. Expl. pi. 40, 



figs. 16-19. 1886. 



This form very closely resembles F. (P.) quadrangular is, and may possibly be 

 only a variety of that species. The longitudinal di.'^position of the cell aper- 

 tures is very distinct, the ranges sometimes being separated by comparatively 

 prominent ridges ; at other times the margin of one side of the cell aperture 

 is very strongly elevated, coalescing with adjacent margins longitudinally, and 

 forming an elevation which has the appearance of a prominent ridge separating 

 the ranges of apertures. 



Formation and locality. Upper Helderberg group. Falls of the Ohio river. 



