182. Dr. H.A. Nicholson on new Species of Polyzoa 
6. Fenestella nervata, Nich. Pl. XIV. figs. 6, 6 a. 
Frond fan-shaped (?), composed of narrow, closely approx- 
imated branches, about four or five of which occupy the space 
of one line. On the non-celluliferous side of the frond are 
two strong, slightly diverging, rounded ribs, about half a line 
in diameter, like the midribs of a multicostate leaf. From the 
sides of these ribs the branches spring obliquely, being directed 
in opposite directions on opposite sides of the rib, with which 
they make a very acute angle (10° or less). Fenestrules long 
and narrow, nearly twice as long as wide, about three in the 
space of one line measured vertically, and about five in the 
same space measured transversely. For the most part the 
fenestrules do not alternate in contiguous rows, but are placed 
opposite one another. The narrow rounded dissepiments 
are thus also placed nearly or quite opposite to one another. 
Branches faintly striated in a longitudinal direction. Cellu- 
liferous side unknown. 
The only example of this species that I have seen is im- 
perfect, and the ribs from which the branches rise are placed 
two lines apart near the base, and four lines apart near the 
summit. It would seem most probable that the nbs sprung 
from a common root, and that there were many of them in the 
pertect frond. The species is distinguished not only by the 
possession of these ribs, but also by the long narrow fenestrules, 
which are not placed alternately, but so disposed that the 
dissepiments connecting contiguous branches become opposite 
or subopposite. 
Locality and Formation.—Summit of the Niagara Forma- 
tion (in beds probably the equivalent of the Guelph Forma- 
tion of Canada), Cedarville, Southern Ohio. Collected by 
Prof. Edward Orton. 
7. Ceramopora ohioensis, Nich. Pl. XIV. figs. 7-7 d. 
Polyzoary incrusting, forming thin expansions attached to 
the surface of Brachiopods and Corals, and consisting, typi- 
cally at any rate, of a single layer of oblique cells. Cells 
arranged in intersecting diagonal lines, and disposed in a 
somewhat concentric manner round more or fewer central 
points; their upper walls thin and arched; the cell-mouths 
oblique and, when most perfect, semicircular in shape. About 
eight cells in the space of one line. 
Such are the appearances presented by this fossil when 
quite perfect; and its examination in this condition leaves 
little doubt as to the propriety of placing it in Hall’s genus 
