402 MOLLUSCA. ARCAD.^. Nucula. 



Length about half an inch, breadth a little more ; cuticle olive-green, with 

 yellow rays ; faintly streaked longitudinally with numerous fine lines of 

 growth. 



** Margin plain. 

 409- N. minma. — Shell oval, transversely striated, with the 

 anterior side produced, curved, and truncated. 



Area oblonga, striata, antice angulata. Walk. Test. Min. ii. t. cxi. f. 81. 



— A. caudata, Don. Brit. Shells, t. Ixxviii — A. min. Mont. Test. Brit. 



140. — N. min. Turt. Biv. Brit. 178 — In deep water, not common. 



Length |ths, breadth |lhs of an inch ; colour white ; three or four strong 



concentric ridges ; beak very small, turning a little towards the augulated 



side, beneath which is a smooth depression reaching to the end. 



410. N. rostrata. — Shell oval, transversely striated, anterior 

 side produced, curved, and slightly ribbed longitudinally. 



Area rostrata, Mont. Test. Brit. Sup. 55, t. xxvii. f 7 — N. ros. Turt. 



Biv. Brit. 178 In the Frith of Forth, Mr Laskey. 



Length half an inch, breadth three quarters; glossy, and of a horn colour; 

 striae fine, regular, and reflected ; from the beaks to the produced extremity 

 the striae are irregular in crossing the longitudinal ribs ; inside polished — 

 In this and the preceding species the central tooth is obsolete. 



411. N. tenuis. — Shell obliquely heart-shaped and smooth. 



Area ten. Mont. Test. Brit. Sup. 5G, t. xxix. £ 1 — N. ten. Turt. Biv. Brit. 

 177 — In the Frith of Forth, Mr Laskey. 



Length scarcely a quarter of an inch ; white, Avith an olivaceous cuticle ; 

 beaks small, slightly inflected ; hinge with six teeth on one side of the cen- 

 tral tooth, and nine on the other ; margin thin. 



EXTINCT SPECIES. 



1. N. CohbaldicE — Transversely' obovate, convex ; surface marked with zig- 

 zag furrows, diverging over the sides; edge entire Sower. Min. Conch. 



I. clxxx. f. 2. — In Crag. 



2. N. lanceolata Transversely ovato-laneeolate, "^smooth ; posterior side 



pointed, edge entire ; a concave deltoid space in the hinge. — Smcer. Min. 

 Conch, t. clxxx. f. 1 — In Cray. 



3. N. Icevigata — Transversely elliptical, convex, smooth ; posterior side 



pointed, edge entire, truncated. — Sower. Min. Conch, t. excii. f. 1, 2. In 



Crag. 



4. N. similis. — Transversely obovate, depressed, obscurely striated longitu- 

 dinally ; posterior side straight ; lunette imbedded ; concave in the middle 

 oblong, edge crenulated — {Area nucleus, Brander, 40. f. 101.) Sower. Min. 

 Conch, t. cxcii. f. 3, 4, 10 — London Clay. 



5. N. trigona. — Ovato-deltoid, compressed, smooth, edge crenulated, hinge 

 pit short ; lunette concave. — Sower. Min. Conch, t. cxcii. f. 5. — Loiidon Clay. 



G. N. minima. — Transversely ovate, convex, transversely striated ; poste- 

 rior side acuminated ; edge entire ; lunette defined, elongated. — Sou-er. Min. 

 Conch, t. cxcii. f. 8, 6. — London Clay. 



7- N. pectinata — Transversely elliptical, elongated, convex ; posterior side 

 truncated ; longitudinally furrowed ; lunette imbedded, flat, cordate ; edge 

 crenulated.— 5'ow'fr. Min. Conch, t. cxcii. f. 6, T.—Chalk Marl. 



