CORALS AND BRYOZOA. 65 



twenty in the space of 5 mm. ; distant less than the diameter of an 

 aperture : margins strong, elevated, those of the marginal ranges indenting 

 the borders of the fenestrules and giving to them a crenulated appearance. 



Width of branches .40 mm., increasing to .75 mm. ; diameter of dissepi- 

 ments .40 mm. ; length of fenestrules about .40 mm. 



This species, in some respects, closely resembles F. (P.) Aria, to which it was 

 formerly referred, but it has a more robust appearance, the cell apertures are 

 more closely disposed, and the ranges are not separated by a carina. 



Formation and locality. In the shaly limestone of the lower Helderberg 

 group, on Catskill creek, Greene county, N. Y. 



Fenestella (Polypora) paxillata. 



PLATE XVIU, FIGS. 10-12. 



FenexteUa paxillata. Hall. Thirty-second Rept. N. Y. State Mus. Nat. Hist., p. 164. 1879. 



7Kipi«ata (in eiTor), Hall. Report of State Geologist for 1 SS2. Expl. pi. IS, figs. 10-12. 188.S. 



Bryozodm observed only in fragments, the form is, therefore, not definitely 

 known. On the non-celluliferous face the branches are slender, at first 

 rounded, becoming flattened and concave for a .short distance before bifurcat- 

 ing, and marked by fine striae. Bifurcations distant. Dissepiments moder- 

 ately strong, rounded, slightly depres.sed below the plane of the branches. 

 Fenestrules sub-quadrangular ; width from one-half to one-third the length. 

 On the celluliferous face the branches are rounded, the dissepiments 

 sub-angular and very much depressed. The fenestrules appear of the same 

 form as on the opposite face. Cell apertures minute, circular ; fourteen in 

 the spjice of 5 mm. ; distant about the diameter of an aperture ; disposed in 

 from two to four ranges ; two ranges occur only for a short distance above 

 the bifurcation, while the greater portion of the branch is occupied by three 

 ranges. The central range or ranges open directly outward, the outer 

 ranges open laterally. 



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



