10 ARCA. ARK. 



brown color, becoming white by exposure to the air: beaks 

 nearly central, incurved, rather remote, with the interme- 

 diate space rhombic black and finely but regularly striate 

 longitudinally; inside white, entire at the margin, with 

 about twenty teeth each side the beak placed in a straight 

 line : length nearly an inch ; breadth something more. 



However averse we may be to the alteration of establish- 

 ed specific names, the uncertainty in which this shell has 

 hitherto stood, and the discovery of its peculiar habitat and 

 history, will we trust hold us justified in this instance. The 

 Linnean Area lactea is described as having the margin 

 toothed, a circumstance which has never been found subject 

 to variation in any shell ; nor on the contrary has any shell 

 with the margin usually plain been found toothed : and 

 from A. barbata and A. reticulata it differs, in having the 

 points of the beaks remote from each other. 



In the summer of 1817, a large mass of very hard calca- 

 reous sandstone, dredged up in Teignmouth harbour, was 

 brought to us, perforated all over the surface, and filled 

 with these shells only, so compactly imbedded that it was 

 necessary to break the stone in order to extricate them, 

 mostly in a living state ; since which they have been found 

 inclosed in rocks about Teignmouth and Dawlish, firmly 

 attached at the front margin by a strong broad deep green 

 film ', and within some of them were found the Tellina sub- 

 orbicularis. This singular habitat may account for the ob- 

 scurity in which this specie/5 has remained, its rarity in a 

 living state, and the variations in its figure ; being some- 

 times angular, sometimes-bounded at both ends, often a lit- 

 tle elongated on one side, sometimes flat, and sometimes 

 very deep and as it were truncated at the front margin : 

 length half an inch j breadth nearly an inch. v. v. 



8. Area fusca. Brown Ark. 



Lister, pi. 367. f. 207 Donovan, pi. 158. f. 3, 4. 



Area Nose. Montagu, pi. 4. f. 3. 



Shell purplish-brown, elongated on one side, finely reti- 

 culate, much resembling Area Noae, but is longer in pro- 

 portion to the breadth, and the longitudinal striae are much 

 finer, except between the angles of the longer end ; and the 

 upper angle of this end is considerably shorter than the 



lower 



