118 PALEONTOLOGY OF NEW YORK. 



disposed dissepiments, there being eleven branches in the same space occupied 

 by seven in that species ; there are twenty cell apertures in the same space occu- 

 pied by fourteen in that species ; from F. interrupta by the more regular appear- 

 ance of the non-celluliferous face and by the absence of prominent, expanding 

 carinoB ; from F. {Reteporina) coalescens by the more closely arranged branches and 

 dissepiments and, iis compared with the branches, much wider dissepiments; from 

 F. {Reteporina) rhombifera by the much closer disposition of the branches and 

 dissepiments, and the narrower dissepiments. It is very similar on its non- 

 celluliferous face to F. labiata of the Hamilton group, and from that face alone 

 it is very difficult to make a satisfactory distinction ; the celluliferous face is 

 very different. 



Formation and locality. Upper Helderberg group, Ontario, Canada. 



Fenestella erectipora. 



plate l, figs. 15, 17. 



PmetUUa erectipora. Hall. Trans. Albany Institute, vol. x, absti-act, p. 32. 1S81. 



" " " Report of State Geolog-ist for 1885, advance sheets. Expl. pi. 50, figs. 15, 17. 



1886. 



Bryozodm infundibuliform, sometimes narrowly, at other times rapidly expand- 

 ing. Branches moderately slender, width above bifurcation .34 to .40 mm., 

 increasing to .50 mm., very gradually enlarging, sinuous or zig-zag, usually 

 connected by short dissepiments, but sometimes anastomosing, angular, with 

 small conical nodes opposite the dissepiments or on the anastomosed portions, 

 sometimes slightly carinated ; bifurcations comparatively distant. Interstices 

 wider than the branches. Dissepiments strong, width .60 mm., rounded or 

 angular, on a plane with the branches, three in the space of 4 mm. Fene- 

 strules oval, length about .70 mm., width .45 to .60 mm. 



On the celluliferous face the branches are slightly and regularly sinuous. 

 Dissepiments rounded, much depressed. Fenestrules smaller than on the 

 opposite face, the length sometimes appearing less than the width of the 

 dissepiment. Cell apertures in two ranges, opening directly outward, fourteen 

 in the space of 5 mm., separated by one and one-half times the diameter of 

 an aperture: margins distinctly elevated. Surface between tlie ranges of 

 apertures carinated, carinaB sinuous, narrow, height about .25 mm. 



