140 PALEONTOLOGY OF NEW YORK. 



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

 aperture : margins distinctly elevated and indenting the borders of the fenes- 

 trules. Carinse thin, height .60 mm. Scaloe very thin, oblique ; outer mar- 

 gin strongly curved, forming a semicircle, the curvature being toward the 

 base of the frond, and oblique in the same direction ; six in the space of 5 mm. 

 Summit of the carina very thin, sometimes straight and distinct, at other 

 times interrupted by the scalsB and indistinct ; sometimes this surface of the 

 frond is so irregular that it closely resembles some forms of Alveolites. 



The obscured or interrupted branches, wide dissepiments and prominent 

 nodes of this species will be sufficient to distinguish it from any other of this 

 geological formation. 



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



Fenestella (Unitrypa) elegantissima. 



PLATE LIII, FIGS. 12-17. 



Fhtegtella (Hemitrypa) elegantissiina. Hall. Trans. Albany Institute, vol. x, abstract, p. 36. 1881. 



" (Unitrypa) " " Report of State Geolojfist for 1885, advance sheets. Expl. 



pi. 53, fiffs. 12-17. 1886. 



Bbyozoum infundibuliform, fronds large. Branches moderately slender, width 

 above a bifurcation .35 mm., increasing to .65 mm., gently rounded or flat- 

 tened, sub-angular, carinated ; carina slightly elevated and with small but 

 very distinct nodes, four in the space of 1 mm. Interstices wider than the 

 branches. Dis.sepiments strong, width from .75 mm. to 1 mm., gently rounded 

 or flattened, slightly depressed, four in the space of 9 mm. Fenestrules 

 oval, length 1.25 mm., width .60 mm. 



On the celluliferous face the branches are rounded, usually sinuous. Dis- 

 sepiments rounded, very much depressed. Fenestrules of nearly the same 

 appearance as on the opposite face. Cell apertures in two ranges, opening 

 directly outward, oblique to the axis of the branch, sixteen in the space of 

 5 mm., separated by less than the diameter of an aperture. Carina3 thin, 1 

 mm. in height. Scalae thin, outer margin forming a semicircular or semi- 

 oval curvature which is convex toward the base of the frond, oblique in the 



