58 TESTACEA. 



deduced merely from views of the huts they have occupied ? Here also 

 is a new feature displayed iu the cultivation of Natural History. To as- 

 certain the precise position of his subject in the Sij-stema Natitra, the 

 animal must be bereft of life, and the carcase scooped out of its native 

 abode, to ascertain what description of hinge connects the valves of the 

 shell, — this being judged one of the most important parts of conchology. 

 The fit mode of proceeding, the selection of what is sufficiently promi- 

 nent as the basis of systematic arrangement, must be admitted as diflicult. 

 But by following the preceding course, we spontaneously contrive an in- 

 superable obstacle to elucidating the history of the living creature. 



Combining the structure of the dwelling with the nature of its 

 dweller, seems a preferable mode of promoting knowledge. Yet, I repeat, 

 the subject is extremely embarrassing, and the wider the view we take it 

 becomes the more so. 



But no subject has been more ardently cultivated in its ruder state 

 than conchology. Many have taken a deep interest, without any scien- 

 tific object, in this subject, in its ordinary acceptation. The formation of 

 cabinets, comprehending a complete series of the various genera, has been 

 as energetically pursued as the exertions of the antiquary in collecting 

 uninterrupted series of coinage to illustrate the history of kingdoms. 



Hence have shells become an ingredient of establLshed traffic, wherein 

 the most extravagant prices may be lavished by the wealthy enthusiast. 

 In truth the singularity and the beauty of some are adnih-able. But the 

 prudence of costly purchases is, at the least, equivocal ; nay, such an in- 

 discretion sometimes generates its own censure, for the fortune of the 

 adventurer for the acquisition of such stock has conducted him of later 

 years to numerous broods of those previously accounted almost unique in 

 the universe ; and a few casks of the precious subjects of discovery have 

 produced an absolute revolution in the commercial interests of both the 

 merchant and the collector. 



It is extremely probable that there are organic distinctions among 

 the bivalves which have hitherto escaped the notice of the naturalist. 

 Abiding by the most conspicuous difference, very few animals inhabit the 

 bivalves, and, with exception of one, the Ascidia, or rather a creature 



