BIVALVIA. 121 



Spec. Char. Testa transversd, elongato-ovatd, tequilaterali, leviter convexd, Itevigata, 

 vel tenuissime striatd; utrinque rotundatd, dente cardinali unico, obtuso ; lateralibus nullis, 

 foved ligamenti elongatd obliqud. 



Shell transverse ovate, equilateral, slightly convex rounded at both extremities, 

 smooth, or with very fine lines of growth ; hinge with one cardinal tooth, no lateral 

 teeth, ligamental area elongated, and oblique. 



Length, fths. Height, T 7 ths. of an inch. 



Locality. Coralline Crag, Sutton. 



Red Crag, Walton Naze, and Sutton. 

 Mam. Crag, Chillesford. 



This shell is abundant in the Coralline Crag, but the specimens are generally small, 

 rarely exceeding half an inch. Fig. 11, b, is from the Red Crag, and measures at least 

 three quarters of an inch. Among a large number of individuals a considerable varia- 

 tion may be observed, but these differences are principally in the proportional dimen- 

 sions, although some specimens have occasionally a more triangular form (fig. 1 1, a). It 

 is furnished with one somewhat prominent but obtuse tooth in the right valve, with a 

 depression before it, and in the left valve there are two teeth, when perfect, which is 

 not often the case, one immediately beneath the umbo, erect and compressed, the other 

 decumbent along the margin and at right angles to the other; the ligamental area slopes 

 obliquely backwards, forming a thickened ridge, against which it rested. The impressions 

 by the adductors are large and rather elongated, while that formed by the edge of the 

 mantle is at some distance within the margin of the shell, and is without any inflection, 

 and in some thin specimens from the Coralline Crag, fine radiating lines are visible in 

 the interior. 



This is the largest species of Kellia that I am acquainted with, and strongly resembles 

 in form a shell from the Paris basin, to which it was assigned in my Catalogue ; but 

 by a comparison with a specimen from the Older Tertiaries of this country, now in the 

 cabinet of Mr. John D'Urban, and which probably is identical with the Psammotea dubia, 

 Desh, a material difference is exhibited sufficient to prove them specifically distinct, as 

 in that shell the ligament is placed on the outside, whereas in ours it is wholly internal. 



A recent species from the Coast of Lower California, described and figured by 

 Conrad in the ' Journal of the Acad. of Nat. Sci.,' Philadelphia, 1850, Art. xxii, p. 279, 

 pi. 39, fig. 1, under the name of Solecardia eburnea, has a strong generic relationship 

 with our Crag fossil, although no doubt specifically distinct. 



4. KELLIA ELLIPTICA, Scacchi. Tab. XII, fig. 13, a c. 



TELLINA ELLIPTICA. Scacchi. Oss. Zool.. ii, p. 14, 1833,1 



( fide Phihppi. 

 LORIPES ELLIPTICUS. Scacchi. Ejusd. Cat., p. 5, fig. 1, J 



LTJCINA OBLONGA. Phil. En. Moll. Sic., vol. i, p. 34, t. 4, fig. 1, 1836. 

 KELLIA FLEXUOSA. S. Wood. Catalogue, 1840. 



J. Sowerby. Min. Conch., t. 637, fig. 5, a, 1844. 

 SCACCHIA ELLIPTICA. Phil. En. Moll. Sic., vol. ii, p. 27, t. 14, fig. 8, 1844. 



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