112 PALEONTOLOGY OF NEW YORK. 



strongly indenting the borders of the fenestrules. Surface between ranges 

 of apertures angular, nodose. 



This species may be distinguished by the depressed dissepiments on both faces 

 of the frond. 



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



FeNESTELLA iEQDALIS. 



PLATE XLVI, FIGS. 27-31. 



FettesUlla mqual'ui. Halt,. Trans. Albany Institute, vol. x, abstract, p. 31. 1881. 



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

 cation .30 mm., increasing to .50 mm., very gradually enlarging, rigid, 

 angular, slightly carinated. Nearly all the specimens observed are par- 

 tially covered by the original rock deposit, leaving only the summits of the 

 branches exposed, giving tliem a very slender appearance ; width not more 

 than .20 mm. : bifurcations distant. Interstices nearlv twice as wide as the 

 branches. Dissepiments comparatively strong, width .30 mm., angular, 

 slightly carinated, on a plane with the branches, five in the space of 5 mm. 

 Fenestrules sub-quadrangular, length 70 mm., width about .50 mm. 



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

 much depressed. Fenestrules smaller and more oval than on the opposite 

 face. Cell apertures in two ranges, eighteen in the space of 5 mm., separated 

 less than the diameter of an aperture : margins thin, slightly elevated. Sur- 

 face slightly carinated and with prominent conical nodes which usually occur 

 opposite a dissepiment, but frequently on other portions of the frond. 



This species may be distinguished by the rigid branches, sub-quadrangular 

 fenestrules, strong dissepiments, and the prominent nodes opposite dissepiments 

 on the celluliferous face. 



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



