Pvn H,i I'UitlS

LIMA. 79
but semitransparent, glossy : sculpture, 25-30 raised concentric
plates or laminae, which are imbricate and partly overlap one
another in succession, the distance between them increasing
in proportion to the period of formation, so that the earliest
ones lie close together; these plates are crossed by about
the same number of slight ribs, which give the surface an
imperfectly cancellated appearance : colour white : margins
rounded, except at the hinge : beaks small, straight and
blunt, projecting beyond the dorsal margin: ears very small
and indistinct : cartilage small, placed
angular pit, which is perpendicular
in a shallow tri-
instead of horizontal as
in the last genus : hinge-line short and straight : hinge-plate
narrow, bluntly but distinctly crenulated across : inside pearly,
grooved by the reflection of the ribs and strongly
crenate or
notched within the front margin : muscular scars slight.
L. 0-125. B. 0-1.
Habitat :
Shetland, in 85 fathoms, with Limopsis aurita
and other rare mollusks. This remote cluster of our sea-
girt isles, which with their craggy fastnesses guard
" The unadorned bosom of the deep,"
has yielded more novelties of the highest interest to
marine zoologists than any other part of the British
coasts. My friend Mr. Waller detected two fresh valves
in some gravelly sand which I dredged in 1862 and sent
to him for examination ;
and I found another specimen
this year on the same ground. The species was first
discovered by Professor Sars at Bergen, and described
by Professor Loven. Danielssen found it at Vadso, in
40-80 fathoms, and Lilljeborg at Christiansund. It is
rare.
In consequence of the hinge-plate in certain fossil
species of Lima being partly toothed or crenulated, the
late Professor Bronn proposed in 1831 to make of them
a new genus, which he called Limea ; and in the fol-
lowing year Miinster described the same genus under
the name of Limoarca. Bronn remarks that, but for
its having only one muscular impression, this genus