CORALS AND BRYOZOA. 137 



in two ranges, opening directly outward, slightly oblique to the axis of the 

 branch, sixteen in the space of 5 mm. : margins elevated, strongly indent- 

 ing the borders of the fenestrule. Carina nearly 1 mm. in height; the 

 lower half very thin, then slightly expanding, width at the summit .20 

 mm. Scalae thin, extending downward nearly to the branch, for a short 

 distance oblique toward the ba.se, then abruptly bending and continuing in 

 the opposite direction, width of the outer portion about .30 mm.; eleven 

 or twelve in the space of 5 mm. Interstices oval, slightly narrower than 

 the scalse. 



This species may be distinguished from any other of this geological formation 

 by the large size of the branches, which are rounded or flattened and some- 

 times nodose ; the carinated dissepiments and the thin scaloe which at the 

 summit are directed obliquely toward the base. From F. {U.) sedans of the 

 Hamilton group, it may be distinguished as follows : the branches are less fre- 

 quent, they are without carinae iind regular rows of nodes or granules : there 

 are only six branches in the same space occupied by from eight to ten in that 

 species. 



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



Fenestella (Unitrypa) ficticius, n. sp. 



PLATE LH, FIGS. 11-15. 



Brvozoom infundibuliform, fronds large. Branches slender, width above a 

 bifurcation .25 mm., increasing to .50 mm., rounded or slightly flattened, 

 sometimes carinated. Interstices of about the same width as the branches. 

 Dissepiments slender, width .30 mm., flattened or gently rounded, frequently 

 with aslight elevation near the upper margin, which extends upon the branches 

 bordering the lower portion of the fenestrule, four in the space of 5 mm. 

 Fenestrules oval, length .80 mm., width .33 mm. 



On the celluliferous face the dissepiments are rounded, carinated, very 

 much depressed. Fenestrules narrower, than 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 somewhat less than the 



