192 CONCHYLIA— D/rj/Fi«^. 41. 



been long exposed to the sun and air, bleached to an ivory 

 whiteness, considerably thickened, deeply and beautifully reti- 

 culate in long squares, where the interstices or softer parts appear 

 to liave been decomposed, and absorbed into the lines of reticu- 

 lation or harder parts. 



The exposed bones of animals undergo a process similar to 

 this: and the antiquary well knows, that in ancient sculptuue 

 on certain stones, probably modifications of lirae, the engrared 

 or indented parts gradually fill up, and at length become level 

 with, or even raised above, the surrounding surface. 



senauim Cabdium tcstd obovatd nittdA sulphured glaberrimu. 



Shell oboval glossy and sulphur yellow, with the ribs quite 

 obliterated. 



Tab. nost. 13. fig. .5. 

 Cardium serratum. Linn. Syst. Nat. p. 112.3. 

 Gmelin, Syst. p. 3251. 

 Turton, Linn. Syst. iv. p. 204. 

 Dillwyn, Descript. Catal. p. 124. 

 Cardium citrinum. Wood, Conch, p. 223, tab. 54, fig. 3. 

 Chemnitz, vi. p. 198, tab. 18, fig. 189. 

 Pectunculus laivis. Lister, Conch. tatK 249, fig. 8.3. 

 Mms. nost. Dredged on tlie western coasts. 



Shell an inch and a half long, and an inch and a quarter broad, 

 very nearly allied to the last, of wiiich it may possibly be oiily a 

 variety; but it is of an uniform rich sulphur yellow, with occa- 

 sionally an orange stain about t\\e anterior margin ; tlie inside 



