Corals and Bryozoans of the Lower Helderberg. 169 



poriferous side rounded, except just below the bifurcations, where they are flat- 

 tened ; striated, striae fine, but very distinct, from five to seven on a branch ; 

 bifurcations distant, irregular. 



Dissepiments, three in the space of five mm., slender; width one-half that of 

 the branches, expanding very slightly at their junction with the branches ; on 

 non-poriferous side striated, and on plane of the branches ; on poriferous side 

 depressed. 



Fenestrules subquadrangular, about four times as long as wide ; width varying 

 from one-half to a little more than the width of the branches. 



Cell-pores in two ranges, round, distant from each other equal to or greater 

 than their diameter, six in the space of a fenestrule, opening obliquely outward ; 

 margins distinctly elevated, and indenting the border of the fenestrule ; space 

 between ranges of pores subcarinate, carina narrow, elevated but slightly above 

 the branch. 



This species is easily recognized by the long, narrow fenestrules, and the 

 slender and frequently crowded appearance of the branches. 



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



Fenestella Adraste, n. sp. 



(PLATE XX, FIGS. 20-22.) 



Bryozoum fan-shaped. Branches moderately strong, eight in the space of 

 five mm. ; on non -poriferous side flattened, striated, from one to three striae on 

 a branch ; where more than one striation occurs, the one nearest the centre of 

 the branch is much the stronger ; very frequently only one striation occurs, in 

 which case it is very strong, giving to the branch a carinate appearance. 



Dissepiments about one-third the width of the branches, six in the space of 

 five mm., much expanded at their junction with the branches. 



Fenestrules oval, width a little less than that of the branches, length from 

 two to three times the width. 



Cell-pores in two ranges, opening nearly directly upward, three in the space 

 of a fenestrule ; distance from each other less than the diameter of an opening, 

 sometimes contiguous ; cell-apertures circular ; margins distinctly elevated, and 

 indenting the borders of the fenestrules ; space between ranges of cells cari- 

 nated, carina sharp, height above the branch equal to the diameter of the 

 branch. 



This species is easily recognized by the flattened branches on the non-porif- 

 erous side, with the strong central striation giving a carinate aspect. 



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



Fenestella Cleia, n. sp. 



(PLATE XX, FIGS. 14, 15.) 



Bryozoum broadly cup-shaped. Branches somewhat rigid in appearance, from 

 nine to eleven in the space of five mm. ; on non-poriferous side subangular near 

 the base, flattened above ; bifurcations frequent. 



