Cardium. 



CONCHIFERA. 



199 



Transversely sub-quadrangular, with a keel running from 

 tlio l)eiik at tlio posterior side to the base ; surface longitu- 

 dinally furrowed, with three or four erect transverse laraclhc, 

 which are pectinated upon their lower sides ; anterior side 

 smooth and truncated. 



The London Clay, Barton. 



10. Cypricaiuiia Deltoide.v. — The Doltoidal, Cypricar- 

 dia, pi. LXXXI. fig. 7. 



C. deltoidea. Phillips, Pal. Fos. p. 37, pi. 17, fig. 59. 

 Portlock, Geo. Rep. pi. 36, fig. 7. 



Ovate, rhomboidal, compressed ; anterior side rounded ; 

 posterior side obliijuely truncated below, with an oblique 

 ridge from the beaks to the base ; beaks obtuse, nearly cen- 

 tral ; base rounded ; surface smooth. 



The Devonian Shales, Petherwin, Cornwall, and the Carboni- 

 ferous Limestone, Tyrone, Ireland. 



11. Cypricardia TnicosTAT.\. — The Three-ribbed Cypri- 

 cardia, pi. LXXXL fig. 13. 



C. tricostata. Portlock, Geo. Rep. p. 441, pi. 34, fig. 17. 



Sluch elongated transversely, moderately inflated ; hinge- 

 line lengthened, and nearly straight ; anterior side short and 

 rounded ; posterior side lengthened, with a pretty strong 

 diasonal ridge from the beak to the margin ; a little above 

 this are two other ridges, and one running parallel, and close 

 to the hintre-line ; surface with irregular concentric stri;e. 



The Carboniferous Limestone, Carnteel, Tyrone, and 

 Drumkeeran, Fermanagh, Ireland. 



Captain Portlock considers this species as highly characteristic of the 

 iron-gray Limestone in which it occurs. 



Genus XXII.— CARDIUM.— XwiwtEMs. 



Shell equivalve, nearly equilateral, and more or less gaping 

 posteriorly ; generally with strong ribs radiating from the um- 

 boncs or beaks to the margins ; inside of the lips crenulated 

 or dentated, corresponding in size to the ribs, two approximate 

 oblique cardinal teeth in each valve, locking into each other 

 cross-ways, and with two remote, lateral teeth in both valves; 

 two lateral, distant, muscular impressions in each valve ; man- 

 tle impressions entire ; ligament external. 



1. Cardium striatum. — The Striated Cardium, pi. 

 LXXXI. fig. 21. 



C. (i) striatum. Sowerby, Silur. Syst. pt. II. p. CI 4, pi. 6.f. 2. 



Shell sub-orbicular, convex, beaks prominent ; surface co- 

 vered with numerous longitudinal, divergent striaj ; length an 

 inch and seven-eighths; breadth an inch and five-eighths. 



In the Aymestry Limestone, near Shelderton, in Lower 

 Ludlow, and also at Aymestrv. 



Murchison mentions a variety of this species larger than the above, 

 more oblique in its form, and provided with more distant and deeper 

 striae ; it is found in the landslip, in Wheeler Vallets Wood, north flank 

 of Brindgwood Chace. 



2. Cardium gentianu.m. — Gent's Cardium, pi. LXXX, f. 1. 



Cardita tuberculata. Sowerby, II. p. 97. pi. 143. 



Heart-shaped, valves equal, laterally compressed, and longi- 

 tudinally sub-carinated, one side somewhat lobated, the other 

 nearly flat ; beaks much incurved ; surface with numerous 

 longitudinal, tubercuiated ribs, placed in sets of three or four, 

 with longer aud more conspicuous ones intervening. 



Upper Greensand, Devizes, and Lyme Regis, Dorset. 



3. Cardium Hillanum. — Hill's Cardium, pi. LXXXII. 

 fig. 3. 



C. Hillanum. Sowerby, I. p. 41, pi. 14, upper fig. 



Nearly circular, a very little wider than long, and slightly 

 oblique; somewhat gibbose, with longitudinal furrows, whicii 

 occupy about a fourth of its breadth on the anterior side ; whole 

 surface with numerous concentric stri;p, the interstices between 

 which are smooth. 



Greensand, Blackdown and Haldown. 



4. Cardium Plumstediense. — The Plumsted Cardium, pi. 

 LXXXI. fig. 22. 



C. Plumstedianum. Sowerby, I. p. 42, pi. 14, right and 

 left hand upper figures. 



Sub-cordate, smooth, anterior side longitudinally furrowed, 

 the serrations on the edge of the shell being rather acute, with 

 transverse, irregular, slightly defined lines of growth, which 

 cover but a fifth of the surface. 



Plastic Clay, Plumsted and Upnor. 



5. Cardium nitens. — The Shining Cardium, pi. LXXXII. 

 figs. 6, 7. 



C. nitens. Sowerby, I. p. 43, pi. 14, lower right hand 

 figures. 



Rather round, anterior side a little produced ; smooth and 

 shining ; surface covered with faint, punctated lines of growth, 

 which are most distinct at the anterior side ; near the base 

 longitudinally striated. 



The London Clay, Highgate and Nuneham. 



6. Cardium angustatum. — The Narrowed Cardium, pi. 

 LXXXII. fig. 8. 



C. angiistatum. Sowerby, III. p. 149, pi. 283, fig. 2. 



Transversely elongated, its length equalling two-thirds of its 

 breadth; thin, somewhat depressed ; anterior side truncated; 

 posterior side rounded ; surface with twenty-seven longitudinal 

 ribs ; margin toothed. 



Red Crag, Sutton ; and Alderton, near Woodbridge. 



7. Cardium kdulinum. — The Small Edible Cardium, pi. 

 LXXXII. fig. 13. 



C. edulina. Sowerby, III. p. 149, pi. 283, fig. 3. 



Thick, almost orbicular; convex, and slightly oblique ; an- 

 terior side a little truncated ; posterior side somewhat pro- 

 duced ; surface covered with eighteen rugose lonnitudinal ribs. 



Differs from C. edule in the form of the anterior side, which is less 

 wedge-shaped, and is somewhat shorter. 



The Red Crag, Sutton, and the Coralline Crag, Ramshot. 



8. Cardium Parkinsoxi. — Parkinson's Cardium, pi. 

 LXXXI. fig. 20. 



C. Parkinson!. Sowerby, I. p. 105, pi. 49. 



Gibbose, somewhat oblique ; posterior side a little parallel ; 

 with thirty-eight to forty longitudinal ribs, with transverse 

 slight elevations on each, which are most prominent towards 

 the margin. 



Differs from C. edule in its more delicate form, and in being less acute 

 at the posterior side. 



Red Crag, Walton. 



9. Cardiu.m proboscideu.m. — The Produced Cardium. |il. 

 LXXXL fig. 19. 



C. proboscidetim. Sowerby, II. p. 127, pi. 156, fig. 1. 

 Gibbose, sub-orbicular; anterior side nearly parallel ; sur- 

 face with about twenty slightly elevated longitudinal ribs, each 



