48 PALEONTOLOGY OF NEW YORK. 



Dissepiments rounded and much depressed. The fenestrules appear larger 

 and more quadrangular than on the opposite face. Cell apertures small, 

 circular, in two ranges, opening laterally; twenty-five in the space of 5 mm., 

 distant less than the diameter of an aperture. 



Formation and locality. Lower Helderberg group, near Clarksville, N. Y. 



Fenestella Alth^a. 



PLATE XIX, FIGS. 17-19. 



Fhiestella Althea, Hall. Thirty-second Rept. N. Y. State Mus. Nat. Hist., p. 166. 1879. 



Report of Stat" Geologist for 1882. Expl. pi. 19, figs. 17-19. 1883. 



Bbyozoum infundibuliform, of somewhat lax growth Branches slender, rounded, 

 marked by fine striae. Bifurcations distant, frequently occurring at intervals 

 of 15 mm. or more. Interstices wider than the branches. Dissepiments 

 very slender, three in the space of 5 mm. ; frequently oblique to the branches. 

 Fenestrules quadrangular, sometimes rhomboidal from the obliquity of the 

 dissepiments. 



On the celluliferous face the branches are angular and the fenestrules 

 appear oval. Cell apertures circular or slightly oval, in two ranges, with 

 additional apertures just below a bifurcation ; about twenty in the space of 

 5 mm. ; distant less than half the diameter of an aperture. 



This species, in some of its features,, closely resembles F. crehripora, but it is 

 of much coarser growth. 



Formation and locality. Lower Helderberg group, Albany county, N. Y. 



Fenestella Adraste. 



PLATE XX, FIGS. 19-22. 



FmetMla Adraste, Hall. Thirty-second Rept. N. Y. State Mus. Nat. Hist., p. 169. 1879. 



Report of State Geologrist for 18S2. Expl. pi. 20, figs. 20-22. 1883. 

 tp. t " Reiwrt of State Geologist for 1832. Expl. pi. 20, fig. 19. 1883. 



Bbvozoum infundibuliform, compact. Branches moderately strong, flat, with a 

 prominent carina along the middle, and on the wider portions of the branch 

 there is occasionally a striation on each side of the carina. Bifurcations 



