CO^CRYLIX—DITHYRA. 7. 29 



We cannot, as yet, agree with Lamarck and the French natu- 

 ralists, that mere difference in shape or outline are always sufficient 

 grounds for strict specific character, circumstances often necessa- 

 rily occasioned by their confinement, and where the different 

 component parts of the rock they inhabit may be of more difficult 

 solution or decomposition. 



A competent knowledge of the rock vshells seems at present by 

 no means to be fully attained or clearly understood : and we feel 

 a conviction that much valuable information remains to be dis- 

 closed by an attentive investigation and comparison of the inha- 

 bitants of submarine masses. Our cabinet contains many curious 

 anomalies, of whose determinate generic and specific fixture we 

 are yet in doubt, and which we have consequently forborne to 

 record. 



Quartz, and the more compact kinds of granite, seem to resist 

 their action, as we have searched in vain for any traces of what 

 are denominated borers, in Guernsea and the adjacent islands, 



Venerupis testd polymorphd, striis transversis antice lamellatis P^^orans. 



longitudinalibusque minutis. 

 Shell variously shaped, with transverse striae which become lamel- 

 lar at the anterior end, and minute longitudinal ones. 



Tab. nost. 2, fig. 15 to 18. 

 Venus perforans. Montagu, Test. Brit. 127, tab. 3, fig. 6. 



Linn. Trans, viii. p. 89. 



Turton, British Fauna, p. 159. 



Pennant, Brit. Zool. iv. p. 211. 



DUlwyn, Descript. Catal. p. 206. 



