A VI 



CONCHIFERA. 



159 



6. LiMSA SEMisuLCATA. — Tlic Half-Furrowed Lima, \A. 

 LXYII. figs. 13, 14.. 



L. semisu/cata. Sowerby, Geo. Traus. 2(1 Series, IV. 

 pi. 11, fig. 10. 



Plwjiostoma semisulcatum. Nilsson, Petrif. Suec. XXV. 

 pi. 11, fig. 3. 



Oblong-ovate, very convex, auricles small, nearly equal ; 

 beaks incurvcil ami short ; disk with a series of twelve to six- 

 teen railiated rouudotl ribs, extending from the beaks to tlio 

 base ; where the lines of growth cross these, they assume the 

 form of short granular scales ; sides smooth. 



The Lower Greensand, Hythe, Blackdown, and Pul- 

 borougb. 



7. Lima exii.is. — The Small Lima. 



L. exUis. AVood, Mag. Nat. Hist. 1839, p. 23'1, pi. 3, fig. 1. 



Ineijuilateral, oblique, slender, gaping at the sides; some- 

 what inflated ; hiuge-line a little oblique, and sloping slightly 

 on both sides of the beaks, which are distant ; ligamental 

 area large, with a rectangular central pit ; lunule smootli 

 surface with numerous, fine, radiating, irregular ribs, whicli 

 project a little over the margins ; tiie interstices with many 

 very fine concentric stria3 ; length and breadth about an inch 

 and a half. 



The Coralline Rag, Ramshot, and the Red Crag, Walton, 

 Essex. 



8. Lima oblo.nt.a. — The Oblong Lima. 



L. oUonga. "Wood, Maij. Nat. Hist. 1839, p. 234., pi. 3, 

 fig. 2. 



Inequilateral, oblique, sub-compressed, gaping at both 

 sides ; hinge-line oblique, sloping on both sides of the beaks, 

 which are prominent and distant ; ligamental area broad, with 

 a pretty large rectangular pit ; auricles with a notch below 

 each ; surface with many slightly waved, longitudinal, diver- 

 gent ribs, projecting a little beyond the margins ; length 

 one inch, breadth six-tenths. 



The Coralline Crag, Ramshot. 



9. Lima fkagilis. — The Fragile Lima. 



L.fragilis. Wood, JIag. Nat. Hist. 1839, p. 253, pi. 3, 

 fig. 3. Brown's Roc. Conch. Brit. p._74,pl. 23, figs. 6, 7, 7.* 



Inequilateral, sub-ovate, very convex, fragile ; one side 

 straight, the other arcuated ; hinge-line oblique ; ligamental 

 area broad, with a large sub-triangular pit for the reception 

 of the cartilage ; auricles small, imperfectly defined ; beaks 

 prominent; whole surface with numerous, slightly undulating, 

 longitudinal stria?, with two or three exceedingly minute in- 

 termediate ones ; length three-fourths of an inch, breadth about 

 one-half inch. 



The Coralline Crag, Sutton, and the Red Crag, Walton, 

 Essex. 



10. Lima plicatcla. — The Plicated Lima, pi. LXI.* f. .33. 

 L. pUcatula. Wood, Jlag. Nat. Hist. J 839, p. 235. 

 Convex, ineiiuilatcral, obliquely ovate, orbicular; anterior 



side truncated ; jiosterior side much produced ; beaks project- 

 ing ; hinge-line a little oblique ; liganienal area small ; lunule 

 transversely crenulated ; surface with fourteen or sixteen 

 rather strong, divergent punctated ribs, which project beyond 

 the margin ; the intervening furrows slightly striated concen- 

 trically ; length two-tenths of an inch. 

 The Coralline Crag, Sutton. 



Sub-Genus.— LIMATULA.— 5'. Wood. 



Shell longitudinal, equivalve, equilateral ; sub-auriculated ; 

 umboncs rather largo and prominent ; ligamental area broad, 

 with a triangular pit for the reception of the cartilage ; sides 

 of the valves close. 



1. LiMATULA ovata. — Tho Ovate Limatula, pi. LXI.* 

 fig. 35. 



L. orata. Wood, JIag. Nat. Hist. 1 839, p. 235, pi. 3, f. 5. 



Equilateral, oblong-ovate, convex ; ligamentary area large, 

 with a sub-triangular cartilage pit ; hinge-lino nearly 

 straight ; beaks projecting ; surface with from six to eight 

 rounded, divergent ribs occupying the centre of the disk, 

 emanating from the beaks, and terminating on tho basal 

 margin, beyond which they project ; sides bulging consider- 

 ably in the centre ; length three-tenths of an inch, breadth 

 two-tenths. 



The Coralline Crag, Sutton. 



2. Limatula sub-auriculata. — The Sub-auricled Lima- 

 tula, pi. LXI.* fig. 34. 



L. suh-auriculata. AVood, Mag. Nat. Hist. 1839, p. 236, 

 pl. 3, fig. 6. Lima sub-auriculata. Brown, Rec. Conch. Brit. 

 p. pl. 2.3, fig. 45. 



Equilateral, oblong- ovate, convex; hinge-lino sloping on 

 both sides of the beaks ; surface with many longitudinal di- 

 vergent strife, the two central ones opaque, larger, and more 

 conspicuous than the others, and visible internally; the basal 

 margin finely crenulated ; length half an inch, breadth one- 

 fourth. 



The Coralline Crag, Sutton and Ramshot. 



Grand Division III. 

 Shells with an elongated marginal ligament. 



Tribe I.— MALLACEA. 



Shells foliaceous, more or less in.-equivalve, with tlio liga- 

 ment marginal, partly linear, and either simple or interrupted 

 by crenulations. 



Genus XXIV.— AVICULA.— Za;«arc/l-. 



Inequilateral, inequivalve, foliaceous, sub-quadrate, and ob- 

 lique ; hinge rectilinear, and produced on each side into 

 straight auriform appendages, with a small indistinct tooth 

 in both valves ; an elongated, marginal, liganientiferous area, 

 widened near its centre ; inside pearlaceous, with one sub- 

 central muscular impression, and a series of smaller ones in a 

 line towards the umbo. 



1. AvicuLA I'APYRACEA. — The Papyraeeous Avicula, pi. 

 LXI.** fig. 11. 



Pecten iiapi/racctis. Sowerby, IV. p. 7j, p). 354,. 



Obliquely sub-ovate, mucli compressed ; valves nearly equal 

 aud flat ; ears large, unequal, rectangular, with broail, diver- 

 gent strife, and rather close, longitudinal strife on the larger 

 ear ; surface with numerous elevated stria;, which are crossed 

 by rather distant lines of growth. 



This is not Aricnla pfi/iyracea of Goldfuss, which I have in 

 plate LXI.* fig. 11, and named A. tennissima, nor is it A. 

 jiafijracea of J. D. C. Sowerby, Geo. Trans. 2d Ser. V. p. 

 13C, pl. 8, fig. 16, as I consider that a Posidonomi/a, and have 

 named it papi/racea, see pl. LXI.** fig. 23. 



