Pvn H,i I'UitlS

CYPRINA.
305
nexuous, occupying rather more than one-third of the circum-
ference : teeth, in the rigjit valve three cardinals, the middle one
strong and short (from which the other two diverge),
rior triangular, and posterior ridge- like ;
the ante-
lateral tooth indistinct ;
the left valve has likewise three cardinals, two of which
on the anterior side are symmetrical and very short, and the
third is laminar and diverges from the centre ;
strong and distinct ; the hinge
lateral tooth
is also furnished with several
irregular tooth-like processes on the anterior side: inside chalkywhite
and nearly smooth: paUial scar broad and shining:
muscular scars large and distinct, but not remarkably deep.
L. 4. B. 4-25.
Yar. crassior. Shell thicker, more round, and somewhat
compressed : epidermis of a darker hue and occasionally pitchblack.
Habitat: Common in sand mixed with mud, on
every part of the British coasts, from low-water mark to
100 fathoms. The variety occurs in Swansea, Cardigan,
and Bideford bays. This species is a member of all our
newer tertiaries, and peculiarly characteristic of glacial
and North
deposits. Every sea of northern Europe
America still contains it in a living state, its southern
limit appearing to be the Boulonnais and Cherbourg. A
more globose variety (C. csqualis, J. Sowerby)
is found
in pliocene strata at Nice and in Sicily. This form is
the C. islandicoides of Lamarck.
Hugh Miller says, in his pleasant l
Sketch-book of
Popular Geology/ that C. Islandica, " although one of
the most common shells of the boulder-clay, is by no
means one of the most common shells at the present
time of our Scottish coasts." This must be a mistake ;
for in the Moray Firth, the scene of the gifted geologist's
labours, recent shells of this species are very much more
abundant than the fossil remains of specimens entombed
in the boulder-clay or " till." But in a postglacial or
raised beach at Goldspie in Sutherlandshire,
brink of high- water mark,
close to the
I noticed that valves were