CONCHIFERA. 
147 
Isocardia Cor. —The Heart Isocardia. 
Plate LXXXIX. fig-. 11. 
Globular, and heart-shaped, slightly wrinkled longitudinally; 
reddish-chestnut, the umbones paler and prominent; inside 
white. Four inches long. Inhabits the Mediterranean and 
British seas. 
Genus 15.—HIATELLA.— Daudin. 
Generic Character. —Equivalve, considerably inequilateral and 
transverse ; gaping at the lower margin; teeth of the hinge 
small, in the right valve; and two oblique somewhat large ones 
in the left valve; ligament external. 
Hiatella arctica. — The Arctic Hiatella. 
Plate LXXXIX. fig. 12. 
Transversely oblong; the apices truncated, with two diver¬ 
gent spiny ridges ; yellowish-white, with decussated striae; in¬ 
side pearlaceous. Half an inch long, and one inch broad. In¬ 
habits the British seas. 
Genus 16.—C YPRICARDIA.— Lamarck. 
Generic Character .—Free, equivalve, inequilateral, oblique, 
or transversely oblong; teeth of the hinge three, situated under 
the beaks, and one lateral tooth below the valve. 
Cypricardia Guinaicci. —The Guinea Cypricardia. 
Plate LXXXIX. fig. 13- 
Transversely oblong, oblique, angulated, white, and cover¬ 
ed with decussated striae; compressed before and the apex 
rounded; yellowish-white. Two inches long. Inhabits the 
coast of Guinea. 
Genus 17.—CARD IT A.—• Lamarck. 
Generic Character. — Shell free, regular, equivalve, inequi¬ 
lateral ; hinge with two unequal teeth ; primary tooth short, 
straight, placed under the umbo ; the other oblique, marginal, 
and elongated. 
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