160 PALAEONTOLOGY OF NEW YORK. 



Fenestella (Polypora) cultellata. 



PLATB XZXTI, riGS. 8-23 ; AND PLATE XLI, FIO. 9. 



FeiuMtMa cultellata. Hall. Trans. Albany Institute, vol. x, abstract, p. 21. 1881. 



" (Polypora) cultellata. Hall. Report of State Geologist for 1882. Expl. pi. 29, figs. 3-22. 1883. 

 " '• " " Report of State Geologist for 1885, advance sheets. Expl. pi. 41, 



fig. 9. 1886. 



Bbyozodm infundibuliform, fronds large, strong ; near the base there are usually 

 elongate projections, which frequently have their distal extremities attached 

 to foreign substances, serving as additional supports to the frond. Branches 

 moderately strong, width above a bifurcation .40 mm., increasing to 1 mm. 

 or slightly more ; angular when perfectly preserved, with a slight carina and 

 occasionally with prominent, oblique, conical nodes ; when slightly worn or 

 macerated they are rounded or flattened and smooth ; bifurcations near the 

 base at intervals of from 10 to 25 mm., at some distance above, from 

 30 to 90 mm. Interstices narrower than the branches. Dissepiments 

 slightly oblique, width .50 mm., five or six in the space of 5 mm., on the 

 same plane and much expanded at their junction with the branches. Fenes- 

 trules broadly oval, sometimes nearly circular, length about .50 mm. 



On the celluliferous face the dissepiments are rounded and depressed, very 

 frequently traversed by narrow channels with sharp margins, which extend 

 for a short distance on the branches. Fenestrules narrower than on the 

 opposite face. Cell apertures in from three to seven ranges, eighteen in the 

 space of 5 mm., very closely disposed, usually in contact ; margins distinctly 

 elevated. At frequent intervals along the middle of the branch the margins 

 of the apertures are prolonged into elongate, sharp, node-like elevations, 

 having a height of about .50 or .60 mm. and a length of .75 mm. 



This species is very abundant at the locality cited, and may be readily dis- 

 tinguished by the peculiar elevations on the celluliferous face, and the channels 

 traversing the dissepiments. 



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



