192 (G. F. LASERON.. 
which at times tend to form two definite longitudinal ridges 
which divide the apertures of the three rows of cells. This 
character is, however,, never so marked as in Fenestella. 
The cells are in three distinct rows, increasing to 4 or 5 
before bifurcation. They are circular in section, and 
restricted somewhat at the apertures, which are small, 
with raised edges, separated from each other by a space 
equal to about twice their diameter; and they may lie 
either on the summit of the protuberances or in the hollows 
between. There are from two to three cells in the space 
of one fenestrule, with generally the addition of another 
one opposite a cross-bar. 
Measurements :—In 10 mm. longitudinally, from 7 to 8 
cross-bars, length of fenestrules rarely above °5 mm., width 
°3 to 5 mm. 
Locality and Horizon:—Branxton (Upper Marine Series). 
Relations and differences:—I know at present of no 
Polypora which is at all comparable with this species. 
In the slightly carinated form of the celluliferous surface, 
it approaches P. carmella Hall,* from the Upper Helderberg 
of America, but differs in most other characters. 
POLYPORA VIRGA sp.nov. (PI. VII, fig. 4, Pl. VIII fig. 2.) 
Description :—Though only known from one fragmentary 
specimen, this is so well preserved, that its characters are 
very apparent. Form of colony not known. Branches 
fairly coarse, flat, bifurcating fairly freely and connected 
by very thin, rounded, rod-like cross-bars. Fenestrules 
rectangular, twice to three times as long as broad. 
Non-celluliferous surface not known. Celluliferous sur- 
face flat and broad, cell apertures circular or slightly oval, 
comparatively large and close, distant from each other by 
sometimes less than their own diameter, the rims not 
J. Hall, (9) Vol. vi, p. 1538, plied, Aes: 
