152 PALjEONTOLOGY OF NEW YORK. 



Oil the celluUferous face the branches are gently rounded. Dissepiments 

 extremely slender, rounded, depressed. Fenestrules much narrower than on 

 the opposite face, frequently appearing as mere slits. Cell apertures in from 

 two to four ranges, twenty-four in the space of 5 mm., distant less than the 

 diameter of an aperture, sometimes nearly or quite in contact; margins 

 strongly elevated ; ranges sometimes separated by a narrow striation. 



This variety will be easily recognized by the narrow interstices of the cellu- 

 Uferous face, the closely disposed apertures and their very prominent margins. 

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



Fenestella (Polypora) adnata. 



PLATE XLI, FIGS. 1-8, 10. 



Fenestdla adnata. Hall. Trans. Albany Institute, vol. x, absti-act, p. 25. 1881. 



" {Polypora) adnata, Hall. Report of State Geologist for 1885, advance sheets. Expl. pi. 41, figs. 



1-8, 10. 1886. 



Bryozoum infundibuliform. Branches moderately slender, width above a bifur- 

 cation about .35 mm., increasing to .45 or .50 mm., very gradually enlarging, 

 anastomosing or connected by very short dissepiments, sinuous or zig-zag, 

 angular, carinated ; carinae slight, those of adjacent branches frequently uniting 

 on the anastomosed portion. Bifurcations distant. Interstices slightly nar- 

 rower than the branches. Dissepiments strong, width .65 or .70 mm., angu- 

 lar, on a plane with the branches, six in the space of 7 mm. Fenestrules 

 oval, length .50 mm., width usually two-thirds the length, sometimes nearly 

 equal to it. This face of the frond frequently presents a reticulated ap- 

 pearance. 



The celluliferous face presents a more regular appearance, the branches are 

 rounded, slightly sinuous, essentially parallel. Dissepiments rounded, de- 

 pressed. Fenestrules smaller than on the opposite face. Cell apertures 

 usually in three ranges, twentj'-two in the space of 5 mm., nearly or quite in 

 contact: margins strong. There are, occasionally, apertures much larger 

 than the ordinary ones. 



