Pvn H,i I'UitlS

166 arcidjE.
not seem expedient to substitute it for the long-established
name given by Lamarck.
1. Pectuncultjs glycy'meris *, Linne.
Area glycymeris, Linn. Syst. Nat. p. 1 143. P. glycimeris, F. & H. ii. p. 245,
pi. xlvi. f. 4-7, and (animal) pi. P. f. 6.
Body nearly round and compressed, yellowish-brown :
mantle thick, covered with minute specks of brown and flakewhite
; it is quite open on the anterior side, and but slightly
contracted on the other side : the edges on the posterior side
are studded with numerous, small, black, eye-like
tubercles :
foot very large, axe-shaped, deeply cloven or folded lengthwise
when not in action.
Shell slightly compressed, very thick and solid, of a dull
hue : sculpture, numerous fine longitudinal striae, and more
remote impressed lines, which are crossed by transverse or
concentric striae, varying in number and strength,
the surface
being thus often reticulated : colour yellowish-white, irre-
gularly mottled with zigzag streaks or blotches of purplish
brown, or marked with spots or longitudinal lines of the same
colour, sometimes of a beautiful pink or lighter tint, and even
rows of
milk-white : epidermis brown and thick, forming
short bristles on the impressed lines in : young specimens mar-
gins rounded on all sides except at the back, where they are
interrupted by the beak and hinge -line : beaks small and prominent,
incurved : ligament dark brown, consisting of eight or
nine bundles, which are placed in a large triangular and grooved
cavity below the beak these bundles are ;
consequently longer
at each end, the shortest being in the middle : hinge-line semi-
circular : hinge-plate also curved, extremely broad and thick,
occupying two-sevenths of the circumference: teeth set obliquely,
six or seven in the adult (besides a few others of a
smaller size) on the anterior side, and nearly as many on the
posterior side, the intermediate space being smooth ; in younger
shells the number of primary teeth is the same, but the middle
area is furnished with four or five minute teeth : inside yel-
lowish, with a purple tinge in some parts, freckled or closely
pit-marked, bevelled towards the margin, which is broad and
strongly notched at the edge : muscular scars very conspicuous.
L. 2-25. B. 2-25.
* A name given by Pliny to a kind of shell-fish.