Corals and Bryozoans of the Lower Helderberg. 171 



distinct ; from four to seven on a branch, frequently granulose ; branches much 

 wider below bifurcations ; frequently four or five contiguous branches bifurcate- 

 at equal distances from the base. 



Dissepiments from one-half to one-third the width of the branches, eight in 

 the space of five mm., slightly expanding at their junction with the branches; 

 on non-poriferous side rounded, on poriferous side angular, and deeply depressed. 



Fenestrules small, subquadrangular, from three-fourths to once and one-half 

 the width of the branches, length twice the width. 



Cell-pores in two ranges, opening nearly directly upward ; cell-openings small,, 

 round, three in the space of a fenestrule, distant from each other more than the 

 diameter of an opening ; margins distinctly elevated, and indenting the border 

 of the fenestrules ; space between ranges of pores carinated, height of carina nearly 

 equal to the diameter of a branch ; top of carina much expanded, especially 

 below bifurcations, with a fine, sharp keel along the middle, and on each edge 

 a row of nodes, which, when worn, present the appearance of minute pores or pits. 



This species is distinguished by the compact and closely arranged branches. 

 Formation and locality. Lower Helderberg group, Schoharie, N. Y. 



Fenestella Coronis, n. sp. 



(PLATE XXI, FIGS. 10-13 ) 



Bryozoum funnel-shaped, undulating, without fenestrules near the base. 

 Branches strong, seven in the space of five mm. ; on non-poriferous side gener- 

 ally angular, sometimes rounded, occasionally granulose, not perceptibly stri- 

 ated. 



Dissepiments about two-thirds the thickness of the branches, five in the space 

 of five mm., slightly expanding at their junction with the branches, angular on 

 both sides. 



Fenestrules variable in shape and size, from quadrangular to oval, and from 

 equal to double the width of the branches. 



Cell-pores in two ranges, openings circular, distant from each other less than 

 the diameter of an aperture, three in the space of a fenestrule, opening nearly 

 directly upward, partially concealed by the carina ; margins distinctly elevated, 

 indenting the borders of a fenestrule ; space between the ranges of pores cari- 

 nated, carina elevated more than the thickness of a branch, hollow, much 

 expanded above, and having a thin, sharp crest. 



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



Fenestella precursor. 



(PLATE XXI, FIGS. 14-18.) 



Fertestella prcecursor, Hall. Twenty-sixth Rep. N.Y. St. Mus. Nat. Hist. p. 94. 1874. 



Bryozoum deep, narrow, funnel-form. Branches strong, seven or eight in the 

 space of five mm. ; non-poriferous side generally flattened, gradually enlarging 



