Cardium. MOLLUSCA. CARDIADiE. 423 



440. C. Icevigatum. — 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. Penn. Brit. Zool. iv. 91. t. lii. f. 40. Moiif. Test. Brit. 80. 



Turt. Biv. Brit. 190 — An inhabitant of deep Avater, 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 ftirrows and strise ; 



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 hal^ breadth a quarter less, white or yellow- 

 ish, tinged with pink or orange retrally ; the longitudinal strise 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. 



i. 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. Plunistedianum — 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 trans- 

 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. Ixxxii. f. 1, 2, and t. Dili. f. 3. — In Grey Wacke 

 Limestone. 



6. C. alceforme Triangular, ventricose, longitudinally ribbed ; retral side 



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

 duced, much compressed, ribbed,— -Vower. Min. Conch, t. Dlii. f. 2. — CarbmiifC' 

 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 eacli.— ^oe^er. Min. Concli. t. clvi. f. 1. — In Green Sand. 



