Nucula. MOLLUSCA. ARCADE. 403 



8. N. ovata Transversely ovate, rather depressed, obscurely striated 



transversely ; lunette slightly impressed, cordate, elongated ; margin entire." 

 —Mant. Suss. 94. t. xbt. £ 26, £7 — In Blue Chalk Marl. 



9. N. variabilis Transversely oval elongated, sometimes oblique, rather 



depressed, smooth ; beaks near one end — Sower. Min. Conch, t. cccclxxv. 

 f. 2 In Oolite. 



10. N. lachryma Ovate, gibbose, smooth ; anterior side produced, point- 

 ed, convex above ; posterior side rounded — Soivcr. Min. Conch, t. cccclxxvi. 

 f. 3 — In Oolite. 



1 1. N. mueronata. — Subrhomboidal, rounded, convex, concentrically sulca- 

 ted, anteriorly mucronated — Sower. Min. Conch, t. cccclxxvi. f. 4 — In Oolite. 



fcj 12. N. angulata. — Ithomboidal, concentrically striated ; most convex near 

 the beaks ; front rounded. — Sower. Min. Conch, t. cccclxxvi. f. 5 — In Green 



Sand. 



13. N. impressa Transversely oval, depressed, smooth ; beaks near one 



extremity ; lunette deeply sunk, convex, elongated ; edges entire — Sower. 

 Min. Conch, t. cccclxxv. f. 3 — Green Sand. 



14. N. antiquata Triangular, rounded, gibbose, antiquated, longitudinal- 

 ly striated ; lunette heart-shaped, sunk ; margin toothed — Sower. Min. 

 Conch, t. cccclxxv. f. 4. — Green Sand. 



15. N. ovum Transversely obovate, ventricose, smooth, anteriorly point- 

 ed. — Sower. Min. Conch, t. cccclxxvi. f. 1. — Lias. 



16. N. ventricosa. — Concentrically sulcated ; anterior side rounded; poste- 

 rior much produced, attenuated ; upon the posterior slope is a broad concave 

 area, bounded by two ridges that run from the beak to the extremity ; sulci 

 fine Sower. Min. Conch, t. cccclxxvi. f. 2 In Oolite ? Northamptonshire, 



17. N. deltoidea Triangular, inflated ; posterior side obliquely truncated, 



flat, pointed ; anterior side short, rounded — Sower. Min. Conch, t. Dliv. f. 1. 

 — Upper Marine Formation, Isle of Wight. 



18. N. inflata Nearly globular, smooth ; the posterior side produced, 



compressed, pointed Sower. Min. Conch, t. dIv. f. 1. — London Clay. 



19. TS.undulata. — Globular, concentrically undulated ; posterior side pro- 

 duced, contracted, pointed Sower. Min. Conch, t. Dliv. f. 3. — Chalk Marl. 



20. N. amygdaloides Transversely elliptical, elongated and sulcated, com- 

 pressed ; sides equal. — Sower. Min. Conch, t. Dliv. f. 4. — London Clay. 



21. N. palnus Transversely elongated, very convex, shining; extremi- 

 ties rounded, equal ; beaks nearly central. — Sower. Min. Conch, t. cccclxxv. 

 f. 1 Carboniferous Limestone. 



22. N. attenuala — Transversely elongated, ventricose ; one end short 

 rounded ; the other produced, with a broad concave area, elevated in the 

 middle along the joint ; the whole covered with regular fine concentric ribs, 

 or striae. Like the last in form — Multarticulate Cockle, lire, ltuth 310, 

 t. xv. f. 5. — In slate-clay of the Independent Coal Formation. 



23. N. gibbosa — Transversely ovate, ventricose, beaks incurved near one 

 end, the other slightly produced and obtuse ; obsoletely furrowed concentri- 

 cally, with irregular distant grooves. — Multarticulate Cockle, lire, ltuth. 

 310, t. xv. f. 6. — In Slatc-clay of the Independent Coal Formation. 



cc 2 



