Corals and Bryozoans of the Lower Helderberg. 165 



Cell-pores in from two to four ranges ; immediately below the bifurcations 

 there are occasionally four ranges, for the distance of one and one-half or two 

 fenestrules there are three ranges, and for the remainder of the distance to the 

 next bifurcation there are two ; where three and four ranges occur, the branch 

 is flattened on the top, and much wider than in the other portion ; the central 

 range or ranges open directly upward, the others directly outward, so that where 

 three ranges occur, in looking directly upon the specimen, the two outer ranges 

 are scarcely perceptible. Pores large, round, closely arranged, five in the space 

 of a fenestrule ; cell-margins thin, but very slightly elevated ; space between 

 ranges of pores and dissepiments obscurely, tortuously striated. 



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

 Fenestella (Polypora) Lil^ia. 



(PLATE XVIII, FIGS. 19, 20.) 



Polypora Libia, Hall. Twenty-sixth Rep. N. Y. State Mus. Nat. Hist., p. 96. 1874. 



Bryozoum fan-shaped. Branches moderately strong, seven or eight in the 

 space of five mm. ; on non-poriferous side rounded, striated ; striae obscure. 



Dissepiments one-half the width of the branches, five or six in the space of six 

 mm., enlarging at their junction with the branches. 



Fenestrules subquadrangular to oval ; width varying from equal to the branches 

 to one-half greater ; length from two to two and one-half times the width. 



Cell-pores in from two to four ranges, large, oval, contiguous, alternating, and 

 forming on the broader part of the branch, oblique intersecting rows; margins 

 very slightly elevated ; generally, on the dissepiment near the junction with the 

 branch, there is a single cell-pore, and occasionally the entire dissepiment is 

 poriferous. 



Formation and localities. Lower Helderberg group, Schoharie, and near 

 Clarksville, N. Y. 



Fenestella Eudora, n. sp. 



(plate XIX, FIGS. 3-10 and ? 1, 2.) 



Bryozoum fan-shaped ; stipe at base nearly one mm. in diameter. Branches 

 moderately strong near base, becoming more slender above ; bifurcations fre- 

 quent and irregular below, becoming more distant above ; on non-poriferous side, 

 branches rounded, striated ; striae obscure, from five to seven on a branch ; from 

 eight to ten branches in the space of five mm. 



Dissepiments, five in the space of five mm. ; width not quite one-half that of 

 the larger branches, expanding at their junction with the branches ; on porifer- 

 ous side of frond slightly depressed, striated. 



Fenestrules quadrangular, variable in width, but generally about as wide 

 as the branch; the more slender the branch, the narrower the fenestrules; 

 length from one and one-half to three times the width. 



