190 MOLLUSCA FROM THE CRAG. 



It appears quite distinct from the preceding, in being flatter or more compressed, 

 and the line of hinge much narrower ; it is also a thinner shell. The exterior markings 

 are much alike in both species, having somewhat flat ridges with narrow spaces between 

 them ; they pass obliquely over the shell from the posterior to the anterior side, some 

 of which run out at the ventral margin, and cut the lines of growth at an acute angle ; 

 the hinge is composed of one large triangularly formed tooth in the right valve, with 

 one anterior lateral tooth at the extremity of the lunule ; in the left valve are two 

 diverging cardinal teeth, with the triangular space between them, and the more distinct 

 lateral tooth, or that which has on the outside of it a depression for the elevated edge 

 of the opposite valve, is on the posterior side. This has also the small auxiliary 

 muscular impression on the anterior side, and the mantle mark is without the least 

 indentation. In the adult shell the margin is crenulated, while the younger specimens 

 have it quite smooth. The two valves are occasionally found united in the less 

 unmixed portion of the Red Crag Deposit at Walton-on-the-Naze. 



18. ASTARTE DIGITARIA, Linnaeus. Tab. XVII, fig. 8 a d. 



TELLINA DIGITARIA. Linn. Syst. Nat., edit. 12, p. 1120, No. 71, 1767- 



Chemn. Conch. Cab. vi, p. 126, t. xii, fig. 121, 1782. 

 LUCINA DIGITALIS. Lam. Ann. sans Vert., t. v, p. 544, 1818. 

 ? Bast. Bord. Foss., p. 87, 1825. 



Phil. En. Moll. Sic., vol. i, p. 33, t. iii, fig. 19, 1836. 



Id. vol. ii, p. 25, 1844. 



Desk. 2d edit. Lam., t. vi, p. 231, 1835. 

 Reeve. Conch. Icon., pi. ii, fig. 65. 



DIGITARIA. S. Wood. Catalogue, 1840. 



CURVIRADIATA. Nyst. Rech. Coq. Foss. d'Anv., p. 6, pi. i, fig. 20, 1835. 



Id. Coq. Foss. de Belg., p. 137, pi. 6, fig. 12, 1844. 

 Ency. Method., pi. 292, fig. 5. 



Spec. Char. Testa minutd; orbiculato-ovatd subceqidlaterali, compressiusculd; striis 

 obliquis incurvis, umbonibus depressis; dentibus lateralibus distinctis ; margine integer- 

 rimo. 



Shell small, roundedly ovate, nearly equilateral, somewhat compressed, covered 

 with elegantly curved, oblique, impressed striae; umbones depressed; lateral teeth 

 distinct ; margin smooth. 



Diameter, f ths of an inch 



Localities. Cor. Crag, Sutton. 



Red Crag, Sutton, Walton-on-the-Naze. 



Recent, Mediterranean. 



Abundant in the Coralline Crag at Sutton, and by no means rare in the more 

 genuine portion of the Red Crag at Walton-on-the-Naze, where I have found the two 

 valves united. The only triflirig difference I can detect between the British fossil and 



