Pvn H,i I'UitlS

LIMA. 77
P. Jacobceus (the famous " pilgrim " scallop)
was at
one time erroneously supposed to be a native of these
seas. It is common in the Mediterranean, and M.
Mace has lately included it in a list of shells which he
has found at Cherbourg. It is distinguishable from the
present species by the ribs of the lower valve being
angular instead of rounded.
Genus II. LIMA* Bruguiere. PI. II. f. 2.
Body oblong : mantle not furnished with ocelli.
Shell equivalve : cartilage external : muscular scar placed
on one side.
Lima and Pecten have nearly the same characters ; but
the value or importance of generic, as well as of spe-
cific differences is comparative and varies in each case.
In the present genus the animal has a bright uniform
colour, while the shell is always white. Both animal
and shell in the other genus are more highly favoured
in this respect and exhibit various hues. The former
has its mantle studded with numerous eyes like the tail
of a peacock, and looks down upon its cousin as a poor
blind creature. The Lima moves or rather darts through
the water like a scallop, but in a contrary posture. The
hinder instead of the ventral end is in front, so that the
mode of its progression may be compared to that of a
fish swimming tail foremost. Some species construct
dwelling-places called " nests " out of fragments of
shells, nullipores, gravel, and other material, which
they ingeniously fasten together by their byssal threads
and attach to the roots of large seaweeds. Several
young ones often occupy the same nest or case ; but
when they become adult each individual has a house of
* A file.