PERMO-CARBONIFEROUS FENESTELLIDA. 193 
exserted. Number of rows three to four, alternating, and 
increasing to five or six before bifurcating. 
Within the space of one fenestrule there are either three 
or four cells, with usually an additional one in the width 
of a cross-bar. | 
Measurements:—In 10 mm. longitudinally 4°5 cross-bars. 
Width of branches from under 1 mm. to 2 mms. just prior 
to bifurcation. Average length of fenestrules slightly over 
2mm., and width 1 mm. 
Locality and Horizon:—Branxton (Upper Marine Series). 
Relations and differences:—The large cell-mouths, and 
the rounded, occasionally long, rod-like cross-bars are the 
chief characteristics of this species. It is most nearly 
related to P. dendroides McCoy,’ but differs particularly 
in the more upright and less diverging habit. 
Genus FENESTELLA Lonsdale. 
FENESTELLA FOSSULA Lonsdale.? (Pils. XIII, XIV.) 
Description:—This species, so far is the finest and most 
delicate of our Australian Henestelle; the branches are 
thin, separated from each other by rather more than their 
own width, and connected at regular intervals by much 
thinner cross-bars. The fenestrules are sub-oval or nearly 
rectangular, about 24 to 3 times as long as broad. The 
non-celluliferous surface is covered by a number of fine 
longitudinal striations. On the celluliferous surface, the 
carina is distinct, rising as a low but practically vertical 
wall, with a smooth, rounded summit, and separating the 
double row of cells. The apertures of these are compara- 
tively small, circular, alternating with those of the next 
row, separated from each other by about twice their own 
width, and their edges do not seem to be exserted as in 
* McCoy, (3) p. 266, pl. 29, fig. 9. 
? Lonsdale, (1) p. 183; (2) p. 269, pl. 9, figs. 1, la. 
M—June 5, 1918. 
