Pvn H,i I'UitlS

164 ARCIDiE.
by a Pinna of the comparatively stout cords or cables
anchored to the sea-bottom.
by which it is permanently
Most of the Conchifera appear to be byssiferous.
A species of Limopsis closely allied to the present
has been taken by Mr. M fAndrew on the coast of Upper
Norway, in from 70 to 100 fathoms, and was referred
by him to the Pectunculus pygmaus of Philippi. Sars
found the same species also on the Norwegian coast, but
considered it to be the P. minutus of Philippi. Both
species are fossil. The L. pygmaea
of Searles Wood
from our Coralline Crag is certainly different from Mr.
f ' M Andrew's shell. In Adams's Genera of Recent Mol-
lusca' the Norwegian species is called " L. borealis,
Woodward." The inside margin of the shells found by
M fAndrew and Sars is notched or crenulated, but in
L. aurita it is plain or entire, and the contour of this
last shell is rather less oblique. Whether the crenu-
lated margin is a specific character in Limopsis may be
open to doubt. Of two species of Astarte {A. sulcata
and A. triangularis) usually having notched edges, a
variety
edges ;
of each is not uncommon which has smooth
and specimens are occasionally found possessing
both characters, or having the inner margin partly
notched.
Genus IV. PECTUN'CULUS % Lamarck.
PL IV. f. 4.
Body nearly circular, or suborbicular : mantle open in front,
as well as on the anterior side, and sometimes folded on the
posterior side into a very short excretal duct ; the other part
of the mantle on the posterior side has its margin furnished
with numerous ocelli or eye-like points : foot large and thick,
* A small scallop (Pliny).