136 MOLLUSCA FROM THE CRAG. 



Shell small, roundedly ovate, oblique, sub equilateral, tumid, smooth, thin, and 

 fragile ; posterior side with one obsolete fold or furrow, one obtuse cardinal tooth. 



Diameter, Jth of an inch. 



Locality. Coralline Crag, Sutton. Recent, North Britain, and ^Egean Sea. 



This is not an abundant fossil, and I have only met with it in the rich Depot 

 at Sutton. 



When my Catalogue was compiled this species had not been recognised in the 

 recent state, and the name then proposed for it being without description, or anything 

 by which it could be identified, must give way to the subsequent one of Professor 

 Forbes. In comparing our fossil with the specimens now obtained in the British Seas, 

 no essential difference can be detected, and there is little doubt of their identity, and 

 when it is considered that the recent shell has been separated into three distinct 

 species, more than ordinary range in variation may be expected ; the fossil is, 

 however, free from the ferruginous covering which obscures some of the characters of 

 the living shell ; the Authors of the ' Hist, of Brit. Moll/ after uniting the three 

 species of Mr. Jeffreys, describe their shell as entirely without a fold, but in the most 

 perfect specimens of our fossil may be seen an obscure inflection upon the posterior 

 side, which is here considered to constitute one of its most determinable characters, 

 and has always been in my Cabinet under the MS. name of Cryptodon, from that 

 resemblance. In the few specimens that I possess no great variation is observable ; 

 the general form is obliquely orbicular, the diameter rather greater when measuring 

 from the umbo to the ventral margin than from the anterior to the posterior side, 

 and in some specimens the outline shows a decided pentangular form. There is one 

 obscure tooth in each valve, like that in the preceding species, and the ligament is 

 placed in a depression beneath the dorsal margin, so that it must have been nearly 

 hidden when the valves were united; the anterior muscle mark is large, and of 

 an ovate form, and not band-like as in Lucina. This shell has much the aspect of 

 Kellia, and might, without much violence to classical arrangement, be placed there, 

 or at least, judging from the characters of the shell alone, it appears to have a 

 nearer relationship to that genus than to Lucina. In the living state it has only 

 been met with as a deep-water shell, both from the ^Egean and the North British 

 Seas, ranging from 20 to 100 fathoms. 



LORIPES,* Poli, 1791. 



LiORIPES LORIPODERMA. Poli. 



TELLINA (sp.). Linn. 

 AMPHIDESMA (sp.). Lam., 1818. 

 THIATISA (sp.). Leach, 1819, 

 LIGULA. Menke, 1830, 

 UNGULINA. Jiosc., 1802. 

 TAR AS? Risso., 1826. 



Ifide Gray. 



Etym. Lorum, a strap, and^e*, a foot. 



