Pvn H,i I'UitlS

242 LUCINID^.
orange tint, and their delicate flounces almost equalling
the ornamentation of the once-prized Venus Dione. The
fry are quite smooth and glossy.
This constituted the type of Turton's genus Myrtea,
and of Leach's genus Cyrachcea. It is the Venus hia-
telloides of Delle Chiaje; and Philippi at first adopted
that specific name, not being aware that the species had
been long previously described by Montagu. Macgilli-
vray considered it to be only the young of L. borealis ;
but it may be readily distinguished from that shell by
its shape, which is triangular instead of circular, by its
beaks being much less prominent, and by the row of sharp
spines on the dorsal margin.
2. L. borea'lis *, Linne.
Venus borealis, Linn. Syst. Nat. p. 1134. L. borealis, F. & H. ii. p. 46,
pi. xxxv. f. 5, and (animal) pi. M. f. 6.
Body clear white :
mantle open from the anterior adductor
to near the posterior muscle, where it is contracted and nearly
closed : labial palps one on each side of the mouth, short, coarse,
thick, nearly cylindrical, and striated : foot placed in the middle
of the ventral area, very narrow, and lancet-shaped at the ex-
tremity.
Shell roundish, more or less tumid, solid and opaque, of a
sculpture, numerous concentric ridges or
dull chalky hue :
ribs, which are not much raised although tolerably sharp ; they
become closer, irregular, and even confluent towards the front
margin in adult specimens, and are somewhat laminar towards
the only other markings appear to be a
the posterior margin ;
few slight and minute concentric fines between the : ridges
colour white : epidermis rather thick, fibrous, puckered, and
: fight yellowish-brown margins obliquely truncate on the anterior
side, and forming nearly a right angle with the dorsal
margin in consequence of the line from the beaks along the
lunule being almost straight, rounded in front, with a slight
tendency to obliquity, and somewhat truncate on the poste-
* Northern.