Pvn H,i I'UitlS

PECTEN. id
of Dr. Gray but not of Chemnitz) resembles the present
species in nearly every respect but that of size. It
may be an arctic variety of P, similis or (more probably)
a direct and (
descendant from the original
stock.
pur-sang '
B. Upper valve nearly flat and concave towards the beak :
hinge-line ribbed obliquely.
9. P. max'imtjs *, Linne.
Ostrea maxima, Linn. Syst. Nat. p. 1144. P. maximus, F. & H. ii. p. 296,
pi. xlix.
Body pinkish-white above and bright red or pink in front :
mantle variously marbled with brown, black, and white : cirri
on the inner margin of the mantle short, white, and arranged
in a single row ; those on the fixed or exterior margin are of
different lengths and arranged in three irregular rows : ocelli
of a greenish- blue or purplish hue, forming two rows, and
numbering from 30 to 35 ; those in the front row are con-
siderably larger than the rest, and correspond with the ribs of
the shell : foot snow-white, short, grooved, with a spatulate
extremity.
Shell nearly circular, except behind, where the projecting
ears give a square outline, equilateral above and nearly so
beneath; upper valve slightly raised in the middle, and
smaller than the lower valve, which is very convex ; it is thick
and solid, glossy in the umbonal region but elsewhere of a
dull hue : sculpture, 15 or 16 ribs in each valve, which radiate
from the beaks, and are strong, and nearly as broad as the interstices
between them ; the ribs and interstices are scored bv
a few parallel striaB, which are more numerous on the lower
than the upper valve ; the whole surface is covered with
minute and close-set thin concentric plates, which are imbricated
or overlap one another like roof-tiles : colour reddish-
brown on the upper valve, with a yellow tint on the lower
both valves are sometimes beautifully mottled or marked
valve ;
with bands, zigzag streaks, and spots of burnt umber, or bright
yellow suffused with a delicate pink hue ; occasionally, but
* Largest.
E