CORALS AND BRYOZOA. 
129 
conical nodes. Interstices of about the same width as the branches. Dis¬ 
sepiments strong, width from .60 mm. to slightly more than 1 mm., on a 
plane with the branches, sometimes angular, with a slight carina, which con¬ 
nects with that of the branches ; at other times flat, and having on the upper 
portion a semicircular elevation, which extends upon the branches; on some 
fronds these are elevated above and continue across the branches, coalescing 
with those of adjacent branches, forming very irregular transverse ridges. 
The dissepiments are so prominent that the branches frequently appear 
merely as short processes connecting the strong transverse elevations, from 
three to five in the space of 5 mm. Fenestrules oval, length usually about 
.50 mm., width .30 to .35 mm. 
The celluliferous face of the frond is very regular. Dissepiments rounded, 
very much depressed. Fenestrules smaller and more regularly oval than on 
the opposite face. Cell apertures in two ranges, opening directly outward, 
eighteen in the space of 5 mm.; closely disposed, separated by less than one- 
half the diameter of an aperture : margins thin, distinctly elevated, indenting 
the borders of the fenestrules. Surface between ranges of apertures carinated; 
carina having an elevation of about .70 mm., extremely thin, slightly expanded 
at a little less than one-lialf the height, then contracting, the summit being 
sharp: margins of the expanded portion of the carina marked by a row of 
concave, triangular nodes, equal in number to the cell apertures. 
This species will be easily recognized by the interrupted appearance of the 
branches on the non-celluliferous face, and the high, thin carinse, with rows of 
nodes; in the latter respect resembling F. biserrulata, but it is distinguished from 
that species by the irregular appearance of the frond, and the much smaller 
fenestrules. 
Formation and locality. Upper Helderberg group, Falls of the Ohio river. 
