Pvn H,i I'UitlS

Genus CYA'MIUM *< Philippi.
CYAMIUM. 257
PI. V. f. 8.
Body somewhat compressed : ecccurrent tube scarcely pro-
jecting beyond the posterior
slender.
side of the shell :
gills large :
foot
Shell oblong, very inequilateral : teeth, in the right valve
one strong and large double cardinal (appearing like two single
teeth in immature specimens), and in the left valve two cardi-
nals ;
rior side.
each valve has an indistinct lateral tooth on the poste-
The type of this genus is a small shell from the Falk-
land Isles, which Philippi described in 1845 as Cyamium
antarcticum. This is the only species known, unless
the British shell which I am about to mention belongs
to the same genus. The ligament in both species is
external. Loven adopted Philippics genus for our shell,
but he did so with
which has a wide European range ;
some doubt, because it was supposed that the ligament
in Cyamium was internal. Forbes and Hanley seem
also to have entertained the latter idea : and thev con-
sequently proposed a new genus, Turtonia,
for the re-
ception of the northern species. Messrs. H. and A.
Adams, in their most useful and elaborate work, ' The
Genera of recent Mollusca/ at first united Turtonia with
Cyamium ; but in the appendix they expressed a different
opinion, and separated them, on the ground that " the
shell of the former is closed at both ends, the ligament
is more exposed than in Cyamium, and it is also provided
with slightly prominent elongated lateral teeth
which are absent in Cyamium" Having several times
examined minutely a series of specimens of C. antarcticum
in the British and Stockholm Museums, I have
arrived at a different conclusion; and, after carefully
weighing the reasons stated by the able systematists
* A little bean.