OF RHYMNEY AND PEN-Y-LAN, CARDIFF. 499 
11. CyctonEma tURBINATUM, sp. nov. (Pl. XXIV. figs. 1, 1a.) 
Ero 
. Shell turbinate ; apical angle 55° ; whorls four in number ; body- 
whorl large, convex, angulated by revolving ridges—on body-whorl 
one near the suture, two prominent ones in the middle, and two or 
three smaller ones near the base; on the preceding whorl three 
ridges—a strong one near the upper suture, one in the middle, and 
a faint one near the lower suture; sutures deep; mouth elliptical, 
long axis vertical, peristome continuous, entire; umbilicus deep, 
bounded by a curved ridge on its inner side; surface covered with 
transverse strie or lines of growth, which cross the longitudinal 
ridges without deflection. 
Remarks. This shell is not likely to be mistaken for any other 
species; but without careful inspection it might pass for a Murchi- 
sonia, from which, however, it is distinguished by its entire peri- 
stome. 
12. Murcutsonia ELEGANS, sp. nov. (Pl. XXIV. fig. 8.) 
Shell slender; apical angle 21°; whorls (six preserved), pro- 
minently keeled, outline concave between line and suture, but con- 
sisting of two close threads. Each whorl slightly overlapped by the 
lower one succeeding it, sutures consequently imbricated and marked 
by a distinctly raised band. Surface finely striated asin M. gracilis. 
Length 3;"; width #,". 
13. MurcuisonIa corPULENTA, sp. nov. (Pl. XXIV. fig. 11). 
Shell conical; apical angle 55°; whorls four in number, convex ; 
hody-whorl very large; keel square, prominent between the suture 
and the middle of the whorl; a faint revolving ridge between the 
keel and the suture; outer lip deeply incised towards the notch, 
below the notch projecting convexly. Surface covered by fine, 
close, thread-like, transverse strie, repeating the outline of the ex- 
terior lip. Where the shell has been removed the cast is round and 
smooth, except for three or four revolving ridges which run parallel 
to the keel and below it: these are not visible on the small portion 
of the shell which remains available for observation. 
Remarks. This shell is very similar to M. subrotundata, Portlock, 
and Pleurotomaria bussacensis, Sharpe, both Upper Cambrian species ; 
but it differs from both in the greater elevation of its spire and in 
having the band much nearer to the suture; the revolving lines 
below the band and visible on the cast, also appear to constitute a 
difference. 
14. Pacnuyrnca spHmrica, Hooker. 
A number of these organisms occur beautifully preserved in the 
Rhymney Grit and in the rocks above and below it. They present 
all the characters of Hooker’s species—the spherical form, smooth 
surface, absence of hilum, thick walls, radiating hexagonal cells, and 
wide variation in dimensions. With them in some cases are 
associated plant-remains, which very much resemble fronds of Rho- 
dymenia ciliata and other Floridean species of Algze, 
