Couni 



CONCHIFEilA. 



tlattisli, wodge-sliapofl, gaping at the antorior end ; liingo of 

 the left valve with an elevated, transversely dilated tooth — 

 that of the right valve with a concave tooth, and a small 

 denticle behind it, destitute of lateral teeth ; two small muscu- 

 lar impressions in each valve ; pallial impression with a large, 

 tonguo-shapcd sinus, emanating from the anterior side, and 

 reaching nearly the middle of the valves ; ligament external. 



1. SpHENiA BiNGHAMi. — Biughaui's Sphenia, pi. XU. figs. 

 U, 4--). 



S.B'inffhami. Brown, 111. Eec. Conch, p. 10+, pi. 42, figs. 

 17, 18, and 22. 



Transversely oblong ovate ; anterior side short and rounded ; 

 posteriorly truncated ; beaks rather prominent, and not quite 

 opposite ; surface smooth. 



The Coral Crag, Sutton. 



2. Sphenia Swainsoni. — Swainson's Sphenia, pi. XC. f. 37. 

 <S. Sicainsoni. Brown, 111. Rec. Conch. Brit. p. 104, pi. 



42, figs. 16, 23, 24. 



Transversely oblong oval, wedge-shaped; anteriorly rounded 

 and short ; posteriorly elongated and truncate ; a concave tooth 

 lying horizontally and pointing inwards ; surface smooth. 



The Pleistocene Marine Formation, Bute. 



TiiiBi: III.— CORBULACEA. 

 Shells inequivalve, the ligament interior. 



Genus XLVIII.—SAXICAVA.—ZrtHjarcX-. 



Shell transverse, irregular in form, generally oblong, inequi- 

 lateral, sub-equivalve, gaping anteriorly ; ligament exterior ; 

 two lateral muscular impressions in each valve ; pallial im- 

 pression interrupted, but not sinuated ; hinge in the young 

 condition with sometimes two or three minute, obtuse, mostly 

 indistinct cardinal teeth, which become obsolete in the adult. 



1. Saxicava rugosa.— The Rugged Saxicava, pi. XC. fig. 

 17. 



S. rugosa. Sowerby, V. p. 101, pi. 466. Brown, 111. Rec. 

 Conch. Brit. p. 103, pi. 47, fig. 1. 



Transversely oblong ovate, gaping at one side ; beaks small, 

 obtuse, and placed near the anterior side ; posterior side sub- 

 truncated ; surface with irregular, rugged, concentric wrinkles. 



The Pleistocene Marine Formation, Dalmuir and Bute, 

 Mammiferous Crag, Thompe, and the Rod and Coral Crags, 

 SuttoD. 



Genus XLIX.— AGINA.— r«;-<ow. 



Shell transverse, oval, equivalve, inequilateral, open at the 

 anterior side ; hinge with a single erect, conic, penetrating 

 cardinal tooth in each valve, destitute of lateral teeth ; liga- 

 ment external. 



1. Agina purpura. — Tiie Purple Agina, pi. XC. fs. 26, 27- 



A. purpura. Turton, Brit. Biv. p. 55, pi. 4, fig. 9. 



Transversely oval ; posterior side obliquely truncated ; 

 beaks prominent, close to the shorter anterior side ; surface 

 with irregular, transverse stria? ; length one-eighth of an inch, 

 brcadtli one-quarter. 



The Coral Crag, Sutton. 



Genus \..—i'X^\)OnA.—Brugu'iere. 



Shell free, thin, internally pearlaceous, inequivalve, trans- 

 verse, inequilateral, the anterior side the longer, sub-rostrated, 

 and slightly gaping at its extremity ; one valve flat, with two 

 internal anterior ribs, and with its anterior margin turned 

 downwards, provided with a single, oblong, obtuse, cardinal or 

 hinge tooth, situate behind the ligament ; the opposite valve 

 concave and destitute of teeth, but furnished with an indistinct 

 cicatrice on which the tooth of the flat valve rests when the 

 shell is closed ; in each valve are two distant, lateral, muscular 

 impressions ; ligament internal, its sides lodged in, and at- 

 tached to an elongated cicatrice, which lies inclined to the an- 

 terior side of the valves ; in some species the cicatrice is pro- 

 duced into an elongated divergent lamina, stretching from the 

 umbo towards the anterior side of the shell, and terminating 

 near the inner side of the anterior muscular impression. 



1. Pandora margaritacea. — The Pearly Pandora, pi. XC. 

 figs. 23, 24, 25. 



P. margaritacea. Turton, Brit. Biv. p. 40, pi. 3, figs. 11-14. 



Transversely oblong ; arcuated ; one valve nearly flat, the 

 other moderately convex ; beaks situate near the anterior side, 

 which is rounded ; surface rather smooth and pearly. 



The Red Crag, AValton Naze, and the Coral Crag, Sutton. 



Genus LI.— CORBULA.— J5;«^«ier«. 



Shell inequivalve, one valve being generally small and flat- 

 tened, the other large and convex ; sub-equilateral, transverse, 

 generally gibbose and close ; each valve usually furnished with 

 a single conical, recurved, ascending, pointed tooth, at the side 

 of which is a small concave depression, very deep in some 

 species, which serves either for the reception of the ligament, 

 or the tooth of the opposite valve; two distant, lateral, some- 

 what irregular muscular impressions in each valve ; pallial 

 impression posteriorly angulated, with a very small sinus ; 

 ligament internal, fixed to the tooth of the lesser valve, and 

 inserted in the depression by the side of the tooth in the larger 

 valve. 



1. CoRBULA OALLiCA. — The Maplc-liko Corbula, pi. XC. 

 figs. 1, 2, 3. 



C. gallka. Lamarck, Ann. du Mus. VIII. p. 466, No. 1. 

 lb. An. Son. Vert. V. p. 497, No. 10. Ercy. Meth. pi. 230, 

 fig. 5, a, h, c. Doshayes, Coq. Foss. p. 49, pi. 7, figs. 1, 2, 3. 



Shell transversely ovate ; the larger valve turgid ; the um- 

 bones with thin, transverse stria; ; beaks smooth ; smaller 

 valve with longitudinal remote raj's. 



Found in the London Clay at Brackleshani. 



2. Corbula longirostru.m. — The Long-beaked Corbula, 

 pi. XCI. figs. 6, 7. 



