258 MOLLUSCA FROM THE CRAG. 
CULTELLUS TENUIS, Philippi. Tab. XXV, fig. 2, a—d. 
Soren tenuis. Phil. En. Moll. Sic., vol. i, p. 6, pl. 1, fig. 2, 1836. 
—_— — Id. En. Moll. Sic., vol. ii, p. 5, 1844. 
— Genuis. Nyst et West. Nov. Rech. Coq. Foss. d’Any., p. 3, No. 4, 1839. Mis- 
print. ? 
— TENUIS. Myst. Coq. Foss. de Belg., p. 46, pl. 1, fig. 5, 1844. 
CULTELLUs cULTELLATUS. S. Wood. Catalogue, 1840. 
a a J. Sowerby. Min. Conch., t. 642, figs. 5—8. 
Spec. Char. “ Testa oblongo-lineari, recta, utrinque rotundatd, tenuissimd ; cardinibus 
latert antico approximatis, in valvuld dextra bidentatis, in sinistra tridentatis.” —Philippi. 
Shell linearly oblong, straight, rounded at both extremities, very thin; very inequi- 
lateral ; two cardinal teeth in the right valve, and three in the left. 
Length, 1+ inch. 
Locality. Cor. Crag, Sutton. 
Red Crag, Walton Naze. 
This shell is rare in my cabinet. Two specimens of the right valve, and one of the 
left, from Walton-on-the-Naze, are all that I have seen. 
The Coralline Crag at Sutton has furnished numerous fragments sufficient to justify 
the belief in their identity with the Belgian fossil and the Mediterranean species, 
but it is not S pellucidus, Penn. M. Philippi’s figure shows a much greater 
inequilaterality than our fossil, one side being four times the length of the other 
(probably an error of the artist). In the Crag shell the proportions are as two and 
a half to one. 
It is somewhat broader or higher on the siphonal side, and equally rounded 
at both extremities. The right valve is furnished with two cardinal teeth, the 
anterior one is vertical and compressed, the other larger and diverging. In the left 
valve are three teeth, the centre one is large, and deeply cleft or bifid, one por- 
tion decumbent, almost parallel with the ligamental fulcrum. The muscular marks 
in my specimens are indistinct. 
The shell to which this appears to bear the nearest relationship (judging alone 
from the drawing of the exterior), is one obtained in the Corea, figured by Messrs. 
Reeves and Adams (So/en albida), ‘ Voy. of the Samarang, 1850,’ p. 84, pl. 23, fig. 15. 
Turacia, Leach, MS. 1819. 
Mya (sp.) Montague, 1803. OstropisMa (sp.) Blainv, 1825. 
Lieuta (sp.) Jd. 1808. Oponcinetus. Da Costa, 1829. 
AmpPHIDESMA (sp.) Lamk. 1818. Cortmya (sp.) dgass. 1842. 
ANATINA (sp.) Id. 1818. Ovontoctnera. Id. 
Ixartra. Leach, MS. 1819. Cineroponta. Herm. 1847. 
Turacta, Blainv, 1825. Rang. 1829. 
