210 



CONCHIFERA. 



side teeth ; those of the latter cleft in the right valve, in order 

 to receive the opposite ones. 



1. PisciDiuM Henslowiana. — Heuslove's Piscidium, pi. 

 LXXXVI. fig. 27. 



P. Hensloieiana. Thompson, Ann. Nat. Hist. YI. p. 5-i. 

 P. appendiculata. Brown, 111. Rec. Conch. Brit. p. 95, pi. 39, 

 fig. 25. 



Obliquely oval, much inflated ; beaks tumid, considerably 

 produced, and somewhat tuberculated ; surface with regular, 

 well-defined, concentric grooves. 



The Pleistocene Fresh-water Formations, Clackton, Stutton, 

 Crapthorn, and Grays. 



2. Piscidium amnicum. — The Favourite Piscidium, pi. 

 LXXXVI. fig. 10. 



P. oUiquum. Brown, 111. Roc. Conch. Brit. p. 94, pi. 39, 

 fig. 22. 



Obliquely oval ; beaks tumid, a little produced ; surface 

 with numerous concentric furrows, which are finely striated. 



The Pleistocene Fresh-water Formations, Grays, Erith, 

 Crapthorn, Clackton, Stutton, and Feversham. 



3. Piscidium pusillum. — The Weak Piscidium, pi. 

 LXXXVI.fig.il. 



P. pusillum. Brown, 111. Rec. Conch. Brit. p. 95, pi. 29, 

 fig. 28. 



Slightly ovate, nearly orbicular, sub-compressed, with pro- 

 minent beaks, obtuse at the points ; sides somewhat flattened ; 

 surface with very fine concentric striaj. 



The Pleistocene Fresh-water Formations, Harwich, Cop- 

 ford, Grays, Clackton, Stutton, and Crapthorn. 



Grand Division III.— TENUIPEDES. 



The mantle barely united before ; foot small, narrow, and 

 compressed ; shell having but a moderate gape. 



Tribe I.— NYMPHACEA. 



Having never more than two primary teeth in the same 

 valve ; shell often gaping slightly at the lateral extremities ; 

 ligament external ; umbones generally projecting outwards. 



Sub-division I. — Destitute of lateral teeth. 



Genus XXXVI —AST ARTE— ^baj^riy. 



Shell sub-orbicular, transverse, equivalve, inequilateral ; 

 hinge with two strong, divergent, cardinal teeth in the 

 right valve, and two unequal primary teeth, and one small, 

 nearly obsolete tooth, together with an indistinct lateral 

 one in the left valve ; two ovate or oblong, remote, lateral, 

 simple muscular impressions in each valve, with a third very 

 small one, situate immediately below the indistinct lateral 

 tooth, or at the end of the posterior external depression, and, 

 in some instances, mingling with the lower termination of the 

 posterior muscular impression, which is always simple and not 

 sinuated ; ligament external. 



1. AsTARTE LURiDA. — The Pale Astarte, pi. LXXXYII. 

 figs. 10 and 42. 



A. lurida. Sowerby, II. pi. 137, fig. 1. 



Convex, transversely oblong, its width being one and a half 

 its length ; depressed ; surface with numerous transverse, 

 unequal ribs; margin internally crenulated ; lunette elliptical. 



Oxford Clay, Scarborough, and Inferior Oolite, Dundry, 

 Oxfordshire. 



2. Astarte elegans. — The Elegant Astarte, pi. 

 LXXXYII. fig. 12. 



A. cleyans. Sowerby, II. p. 8G, pi. 137, fig. 3. 



Convex, transversely oblong ; disk depressed ; surface with 

 numerous small, transverse ribs ; lunette cordate ; margin 

 internally crenulated. 



Differs from C, lurida, in the front being more rounded, the back less 

 rounded, and the teeth are more distant. 



Coralline Oolite, Malton, Yorkshire ; the Inferior Oolite, 

 Yeovel and Brora, and the Lias, Prees and Whitby. 



3. Astarte cuneata. — The Wedge-shaped Astarte, pi. 

 LXXXYIL fig. 31. 



A. cuneata. Sowerby, II. p. 86, pi. 137, fig. 2. 



Gibbose, somewhat heart-shaped, or sub-triangular; back 

 broad and flattened ; anterior side produced ; lunette heart- 

 sliaped ; margin entire within. 



The Greensand, Blackdown, and Portland Sand, Tisbury 

 and Garsington. 



4. Astarte excavata. — The Excavated Astarte, pi. 

 LXXXYII. fig. 22. 



A. excavata Sowerby, I. p. 57, pi. 233. 



Convex, obovate, nearly one-third wider than long ; ante- 

 rior side truncated ; back arched ; beaks ill-defined, greatly 

 inclined to the posterior side, which is small ; lunette hemi- 

 spherical ; excavated ; cartilage enclosed in a deep furrow, 

 bounded by sharp edges, which nearly approach each other ; 

 margin toothed ; surface with flat, transverse ribs, which, in 

 the anterior side, run into irregular undulations ; teeth slightly 

 striate. 



The Inferior Oolite, Dundry, Somersetshire, and the Lias 

 of Banz. 



5. Astarte nitida. — Shining Astarte, pi. LXXXYII. f. 8. 

 A. nitida. Sowerby, I. p. 37, pi- 521, fig. 2. 

 Somewhat depressed, transversely obovate ; angular above ; 



beaks pointed ; lunette lanceolate ; surface plain, and rather 

 minutely sulcated near the beaks; edge crenulated. 

 Coi-alline Crag, Ramshot. 



6. Astarte bipartita. — The Double-parted Astarte, pi. 

 XXXYII. fig. 7. 



A. bipartita. Sowerby, YI. p. 38, pi. 521, fig. 3. 



Globose ; obcordate ; beaks acute ; lunette large, short, 

 concave, and smooth ; surface with from six to eight large, 

 flat, transverse ribs, placed on the flat space near the beaks ; 

 internal edge crenulated. 



Coralline Crag, Ramshot. 



7. Astarte oblonga. — The Oblong Astarte, pi. 

 LXXXYII. fig. 15. 



A. oblonga. Sowerby, YI. p. 38, pi. 521, fig. 4. 



Convex ; transversely oblong ; beaks small, and not very 

 prominent ; lunette heart-shaped, pointed, and concave ; sur- 

 face with large, transverse ribs ; interior edge crenated. 



