40S 
MOLLUSCA. ARCADE. 
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. mimita. — Shell oval, transversely striated, with the 
anterior side produced, curved, and truncated. 
Area oblonga, striata, antice angulata, WalTc. 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 fths, breadth |ths of an inch ; colour white ; three or four strong 
concentric ridges ; beak very small, turning a little towards the angulated 
side, beneath Avhich 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. 
Licngth half an inch, breadth three quarters ; glossy, and of a horn colour ; 
strise 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In this and the preceding species the central tooth is obsolete. 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. 56, t. xxix. f. 1 — 1ST. ten. Turt. Biv. Brit. 
177* — In the Frith of Forth, Mr Laskey. 
Length scarcely a quarter of an inch ; white, with 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. CohhaUice. — Transversely, obovate, convex ; surface marked with zig- 
zag furrows, diverging over the sides; edge entire. — Sower. Min. Conch, 
t. clxxx. f. 2 In Crag. 
2. N. lanceolata — Transversely ovato -lanceolate, '^smooth ; posterior side 
pointed, edge entire ; a concave deltoid space in the hinge. — Sower. Min. 
Conch, t. clxxx. f. 1 — In Crag. 
3. N. IcBvigata — Transversely elliptical, convex, smooth ; posterior side 
pointed, edge entire, truncated — Sower. Min. Conch, t. cxcii. 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. — London Clay. 
6. N. mmma.— -Transversely ovate, convex, transversely striated ; poste- 
rior side acuminated ; edge entire ; lunette defined, elongated.— Aowm Min. 
Conch, t. cxcii. f. 8, Q.— -London Clay. 
7. N. -pectinata — Transversely elliptical, elongated, convex ; posterior side 
truncated ; longitudinally furroived ; lunette imbedded, flat, cordate ; edge 
crenulated.— Min. Conch, t. cxcii. f. 6, *^..<^Chalk Marl. 
