Cardium. MOLLUSCA. CARDIAD^E. 423 



440. C. kevhgatum. — Shell subovate, the ribs obscure and 

 obliterated anteally ; covered with a brownish-olive glossy cu- 

 ticle. 



Pectunculus subfuscus, List. Conch, t. cccxxxii C. laev. Linn. Syst. i. 



1123. Perm. Erit. Zool. iv. 91. t. lii. f. 40. Mont. Test. Brit. 80. 

 Turt. Biv. Brit. 190. — An inhabitant of deep water, on various parts 

 of the coast. 



Diameter about two inches ; slightly truncated retrally, and produced at 

 the anal angle ; ribs faint, depressed ; crossed by unequal furrows and stria? ; 

 the shell, when young, is more produced, and of a uniformly greenish-yellow. 



— 441. C. serratum. — Shell ovate, lengthened, glossy, and ap- 

 parently smooth. 



Pectunculus laevis, Test. Conch, t. ccxlix — C. ver. Linn. Syst. i. 1123. 

 Turt. Biv. Brit. 192. t. xiii. f. 5 — West of England and Pentland 

 Frith. 



Length about an inch and a half, breadth a quarter less, white or yellow- 

 ish, tinged with pink or orange retrally ; the longitudinal stria? are minute, 

 the margin crenulated on the ventral, and serrated on the oral edge. 



442. C. edentulum. — Subovate, a single oblique tooth at 



the hinge, with a lateral plate on each side. 



Mactra radiata, Don. Brit. Shells, t. clxi. — C. ed. Mont. Test. Brit. 

 Sup. 29. — Found by Mr Laskey on Langston beach, near Portsmouth, 

 after a severe storm in 1800. 



EXTINCT SPECIES. 



1. C. Hillanum. — Shell nearly circular, a little oblique, with numerous 

 concentric striae, retral edge straightish, longitudinally furrowed. — Sower. 

 Min. Conch, t. xiv. upper fig. — Green Sand. 



2. C. riumstedianum — Subcordate, smooth, retral part longitudinally fur- 

 rowed. — Sower. Min. Conch, t. xiv. middle fig. — Plastic Clay. 



3. C. nitens — Roundish, hind end rather shouldered ; smooth, shining ; 

 marked all over with faintish longitudinal punctated lines, which are rather 

 more distinct at the retral side. — Sower. Min. Conch, t. xiv. lower fig. — Lon- 

 don Clay. 



4. C. Parkinsoni. — Gibbose, rather oblique, posterior side straightish ; sur- 

 face slightly rugose, with nearly forty longitudinal ribs, having slight traus- 

 verse risings on each. — Sower. Min. Conch, t. xlix. — In Crag. 



5. C. Hibernicum. — Very broad and deep ; retrally truncated, concave, with 

 a central eminence ; anteally elongated, beaks incurved, small ; striated lon- 

 gitudinally, the intervening spaces or ribs flat, with obsolete transverse 

 scales. — Sower. Min. Conch, t. lxxxii. f. 1, 2, and t. Dlii. f. 3. — In Grey Wacko 

 Limestone. 



0. C. alceforme — Triangular, ventricose, longitudinally ribbed ; retral side 

 truncated, produced, near the hinge ; concentrically ribbed ; anteally pro- 

 duced, much compressed, ribbed. — Sower. Min. Conch, t. Dlii. f. 2 — Carbonife- 

 rous Limestone. 



7. C. proboscideum Suborbicular, gibbous ; retral side straight, about 



twenty longitudinal rows of large canaliculated spines, with two rows of 

 lesser ones between each — Sower. Min. Conch, t. clvi. f. 1. — In Green Sand. 



