FAMILY CARDIDZ — CARDIUM. 207 
CaRDIUM MORTONI. 
PLATE XXIII. FIG 251. 
(STATE COLLECTION.) 
Cardium mortoni. Conrap, Jour. Acad Nat. Sc, Vol. 6, p. 259, pl. 11, figs. 5, 6, 7. 
Cc: id. Goucp, Invertebrata of Mass. p. 91. 
Description. Shell small, thin, inflated, globular, slightly oblique. Surface smooth and 
destitute of ribs or rays: posterior side somewhat obliquely extended ; margin entire, or ob- 
soletely serrated ; beaks large, tumid, subcentral, contiguous. 
Color. Epidermis scanty, dingy-white ; beneath which it is yellowish, the beaks yellow: 
an oblong dark purple spot on the posterior side. Interior with faint radiating strie: the 
cavity bright sulphur yellow; margins white. 
Length and breadth, 0°5 —0°9. Diameter, 0°3 — 0°6. 
This is a very common shell along the shores of Long island sound. It is closely allied to 
the C. levigatum of the Antilles, according to Dr. Gould, but wants the purple blotch on th« 
posterior margin, and is more smooth and polished on its surface. 
(EXTRA-LIMITAL.) 
C. fasciatum. (Monracu, Suppl. 30, pl. 27, fig. 6.) Shell ovate-rotund, pellucid. Valves with 
about 27 longitudinal ribs, and a few distant elevated strie, which are often obsolete towards the 
hinge. Color, whitish, with transverse interrupted brown bands, which appear, especially within, 
like series of oblong spots. Length, 0-25; width, 0+4. Common to both Continents. 
C. muricatum. (Lin. p. 1123. Lam. Vol. 3, p. 626.) Shell ovate, heart-shaped. Valves with 36 
ribs, of which 12 have their spines directed in an opposite direction to the others; marginal ser- 
ratures largest on the anterior edge. Color, greyish or yellowish white, edged with orange-yellow 
or scarlet on the anterior side, and sometimes stained with red. Length, 1*5; width, 1-4; diame- 
ter, 10. South Carolina, Florida. 
C. ventricosum, Brug. (Lam. Vol. 3, p. 627.) Shell ventricose, almost heart-shaped. 33 — 34 ribs, 
of which seven at the anterior end are flattened and somewhat imbricated, and a few at the posterior 
end are without the scaly strie which cross the others; one edge of the middle ribs is more rounded 
than the other, and they all form crenatures on the margin of the shell. Color, rusty spotted, and 
irregularly banded transversely with biown. Length, 2*2-4+5: width, 2°0-4:0; diameter, 
1-7-—3°5. South Carolina. 
