26 
the men call “‘ Clocks*.”” I have another specimen from 
St. Douat’s Casile, Glamorganshire, by favour of the Rev. 
W.. Traherne. Fig. 2 is a young specimen from the ruins 
of the keep of Cardiff Castle, which was built by Robert. 
Fitzhammon, A. D. 1110. Such were found also at Barry 
Island, in 1792, by Miss Hill. The stone is very like 
the other. 
PLAGIOSTOMA cardiiformis. 
TAB. CXIlL.—Fig. 3. 
Spec. Cuar. Gibbous, nearly circular, longitudi- 
nally furrowed, smooth; anterior side short, 
straight; wings equal. 
a ae ace cr ce 
So fine are the transverse stria in this shell, that they are 
nearly lost, except at the bottoms of the furrows, where 
they look like rows of very minute dots; this is a direct 
shell, with nearly equal sides, a little longer than wide ; the 
margin is toothed within: it is nearly related to P. spinosa, 
tab. 78, having in common with that, much of the general 
form of a Cardium. Depth of a single valve about one- 
third of the length. 
The great Oolite stratum contains also, larger and lighter 
or darker coloured specimens of this Plagiostoma, than the 
one I have figured. I am indebted to the Rev. H. Stein- 
hauer for several specimens from Petty France, in Glouces- 
tershire, — 
* In a quarry near is the cone-eoral Limestone mentioned in British 
Mineralogy, vol. 2, tab. 149, passing into striated Limestone or striated 
Spar, the local term for which is ‘‘ Charrow-bed.”’ Pickeridge Hill, 
mentioned before at pp. 177, 190, and 228, is in the parish of Corffe, four 
miles S. of Taunton, Somersetshire. 
