CORALS AND BRYOZOA. 115 



there is a prominent conical node below each bifurcation. Interstices nar- 

 rower than the branches. Dissepiments slender, width .20 to .25 mm, 

 usually rectangular to the branch, but sometimes oblique, rounded, on a plane 

 with the branches, eight or nine in the space of 5 mm. Fenestrules oval, 

 length from .35 to .40 mm., width from .20 to .25 mm. 



On the celluliferous face the dissepiments are angular, depressed, com- 

 paratively strong. Fenestrules narrower than on the opposite face. Cell 

 apertures in two ranges, opening laterally, twenty in the space of 5 mm., 

 separated by less than the diameter of an aperture : margins slightly elevated. 

 Surface between the ranges of apertures angular, elevated. Below each bifur- 

 cation, and sometimes on other portions of the branch, there is a strong node 

 similar to those on the opposite face. 



This species may be distinguished by its prominent nodes which usually 

 occur immediately below a bifurcation on both faces of the frond. 



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



Fenestella proceuitas, n. sp. 



PLATE XLVI, FIGS. 32, 35, 36. 



Bryozoum infundibuliform, fronds large. Branches slender, width above a 

 bifurcation .25 mm., increasing to .50 mm., very gradually enlarging, the 

 increa.se in size often scarcely perceptible, straight, rounded, with very fine 

 granulose striations and small nodes ; bifurcations distant. Interstices much 

 wider than the branches. Dissepiments very slender, width .20 mm., 

 rounded, finely striated, very slightly expanded, nearly on a plane with the 

 branches, four in the space of 5 mm. Fenestrules sub-quadrangular, length 

 from a little more than 1 mm. to 1.60 mm., widtli .45 or .50 ram. 



On the celluliferous face the branches are angular. Dissepiments angular 

 and much depressed. Fenestrules somewhat narrower than on the opposite 

 face. Cell apertures in two ranges, opening laterally, fifteen in the space of 5 

 mm., separated by a little more than the diameter of an aperture : margins 

 very thin, slightly elevated. Surface between ranges of apertures sharply 

 angular, elevated about .18 mm. 



