60 PALEONTOLOGY OF NEW YORK. 



circular, in two and three ranges, opening directly outward, eighteen or twenty 

 in the space of 5 mm., separated by less than the diameter of an aperture. 

 Three ranges of apertures usually occur, only for 1 or 2 mm. on the branch 

 before bifurcating, but sometimes the intermediate range extends for 4 or 

 5 mm. : margins elevated, indenting the borders of the fenestrules. Branch 

 with a very slight carina between the ranges of cell apertures. 



This species is distinguished by its closely arranged, sub-parallel branches, 

 distant bifurcations, and its rigid appearance. 



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



Fenestella (Polypora) Idothea. 

 plate xix, figs. 14, 15. 



Polypora elegansf Hall. Twenty-sixth Rept. N. Y. State Mas. Nat. Hist., p. 97. 1874. 

 Feneslella Idothea, " Thirty-second Rept. N. Y. State Mus. Nat. Hist., p. 1(56. 1879. 



" •' Report of State Geologist for 18S2 Expl. pi. 19, tijfs. 14, 15. 1883. 



Bryozoum observed only as flattened fragments, the form of a perfect specimen 

 is, therefore, not definitely known. Br.anches moderately slender, rounded 

 on the non-celluliferous side, and marked by fine strias. Bifurcations fre- 

 quent. Width of interstices greater than that of the branches. Dissepi- 

 ments slender, rounded, six in the space of 5 mm., expanded at their junction, 

 and on the same plane as the branches. Fenestrules sub-quadrangular, longer 

 than wide. 



On the celluliferous face the branches are angular or sub-angular, appear- 

 ing stronger than on the opposite face. Dissepiments rounded, sometimes 

 angular and depressed. Cell apertures oval, in two and three ranges, open- 

 ing laterally, length nearly twice the width, and separated by a space equal 

 to one-half the length of an aperture, from eighteen to twenty-two in the 

 space of 5 mm. : margins slightly elevated, not indenting the borders of the 

 fenestrules Between the ranges of apertures, the branch is rounded or 

 sub-angular, and marked by very fine tortuous striae. 



Width of branch above a bifurcation .25 mm., increasing to .40 mm.; 

 diameter of dissepiments .20 mm. ; length of fenestrules from .40 to .60 mm. ; 

 width from .30 to .40 mm. 



