150 PALEONTOLOGY OF NEW YORK. 



This species may be distinguished from F. (H.) columellata, by the more 

 distant branches and dissepiments, and consequent larger fenestrules, there 

 being only nine dissepiments in the same space occupied by fourteen in that 

 species; from F. (H.) favosa, by the much wider dissepiments and their greater 

 distance, the dissepiments of that species being very slender ; from F. (H.) nana, 

 by the same characters that distinguish it from F. (H.) columellata ; from F. 

 {H.) cribrosa, by the wider and more distant dissepiments ; from all the species 

 at present known it is generally distinguishable by the much coarser appear- 

 ance of the frond. 



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



POLYPORA, McCoy. 1845. 



B. Species having more than two ranges of cell apertures on the branch. 



a. Forms having two and three ranges of cell apertures. 



Fenestella (Polypora) celsipora. 



PLATE XLI, FIGS 16-22 ; AND PLATE XLII, FIG. 5-10. 



Fenestdla celsipora, Hall. Trans. Albany Institute, vol. x, abstract, p. 24. 1881. 



(Polypora) celsiporat Hall. Report of State Geologist for 1882. Expl. pi. 33, figs. 5-8. 1883. 

 " " J " Report of State Geologist for 1882. Expl. pi. 33, figs. 9, 10. 1883. 



" •• «< " Report of the State Geologist for 1885, atlvance sheets. E;cpl. pi. 41, 



figs. 16-22. 1886. 



Brtozoum infundibuliform, fronds large, with frequent, strong, radial undula- 

 tions. Branches moderately slender, very gradually increasing in size, 

 rounded or sub-angular, occasionally granulose ; width above a bifurcation 

 .25 to .30 mm., increasing to .50 or .60 mm., bifurcations at intervals 

 of from 15 to 40 mm. Interstices usually wider than the branches, some- 

 times twice the width. Dissepiments comparatively strong, width varying 

 from .33 to .50 mm., rounded, granulose, five in the space of 5 mm., on 

 the same plane with the branches and expanded at their junction. Fenes- 

 trules variable in size, broadly oval or sub-quadrangular, width from two- 

 thirds to three-fourths the length, sometimes the two dimensions are nearly 

 or quite equal. 



On the celluliferous face the branches are sub-angular. Dissepiments 

 slender, depressed. Fenestrules much narrower than on the opposite face. 



