CORALS AND BRYOZOA. 139 



the appearance of being composed of oblique, imbricating, walled cells. Fre- 

 quently the frond is broken in such a manner, that the under side of the 

 carinas and scaljB are shown, when they present precisely the same appear- 

 ance as the non-celluliferous face of some frond of a species having very 

 slender, angular branches, strong, rounded dissepiments and nearly circular 

 fenestrules. 



The character of the scalag separates this species from all others of this for- 

 mation, except F. (U.) pemodosa and F. (U) ekganiissima ; from the former of 

 which it is distinguished by the more regular branches, narrower, more rounded 

 dissepiments and the lines of nodes on the branches ; from the latter, by the 

 more slender branches and dissepiments, smaller fenestrules and the ornamenta- 

 tion of the branches. 



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



Fenestella (Unitrypa) pernodosa. 



PLATE Llir, FIGS. 1-11. 



Fenestella {Hemitrypa) pemodoaa. Hall. Trans. Albany Institute, vol. x, absti-act, p. 35. 1881. 



" ( Unitryya) " " Report of State Geologist for 1885, advance sheets. Expl. pi. 



53, figs. 1-11. 188(5. 



Bryozoum infundibuliform, fronds large. Branches slender, width above a bi- 

 furcation about .30 mm., scarcely increasing in size until just before bifur- 

 cating, when the width is from .50 to .60 mm., sub-parallel, rounded or 

 sub-angular, ornamented with prominent nodes, irregularly disposed, but 

 usually at varying distances along the middle of the branch. Interstices a 

 little wider than the branches. Dissepiments strong, width .75 mm., flattened 

 or gently rounded, a little depressed, occasionally nodo.se ; when the dissepi- 

 ments of a brancli are opposite to each other the branch has the appearance 

 of a slight ridge crossing the dissepiments. Fenestrules oval, length .90 mm., 

 width about .45 mm. 



On the celluliferous face the branches appear stronger, usually sinuous. 

 Dissepiments rounded, much depressed. Fenestrules narrower than on the 

 oppo.site fjice. Cell apertures in two ranges, opening nearly directly outward, 



