TESTACEOUS FISHES. 



the art of the animal; or rather upon its in- 

 stincts ; which, in the same kinds, are ever 

 invariable. The shell generally hears some 

 rude resemblance to the body upon which it 

 has been moulded. Thus, it is observable in 

 all sea-shells, that if the animal has any tu- 

 mour or excrescence on its body, it creates 

 likewise a swelling in that part of the incrus- 

 tation to which it corresponds. When the 

 animal begins to alter its position, and to 

 make new additions to its apartments, the 

 same protuberance which had raised the shell 

 before in one part, swells it again at some lit- 

 tle distance; by which means we see the 

 same inequality, in a spiral line, all -round 

 the shell. Sometimes these tumours of the 

 animal are so large, or so pointed, that those 

 which rise over them in the incrustation, ap- 

 pear like horns: after this the animal disen- 

 gages itself from its first cavities, and then, 

 by fresh evacuations, assumes a new set of 

 horns; and so increases the number in pro- 

 portion to its growth. If, on the other hand, 

 the body happens to be channelled, the shell 

 that covers it will be channelled likewise; if 

 there be any protuberances in the body, which 

 wind in a spiral line about it, the shell will 

 likewise have its tumours and cavities winding 

 round to the end. 



In this manner, as the animals are of vari- 

 ous forms, the shells exhibit an equal variety. 

 Indeed, the diversity is so great and the 

 figures and colours so very striking, that seve- 

 ral persons, with a kind of harmless indolence, 

 have made the arrangement of them the study 

 and the business of their lives. Those who 

 consult their beauty alone, take care to have 

 them polished, and to have an external crust, 

 or periosteum, as Swammerdam calls it, 

 scoured off fro:n their surfaces by spirit of 

 salt. But there are others that, with more 

 learned affectation, keep them exactly in the 

 state in which they have been found, with 

 their precious crust still round them. The 

 expense men have sometimes been at in 

 making such collections, is amazing; and 

 some shells, such as the Stairs-shell, or the 

 Admiral-shell, are not more precious for their 

 scarceness, than pearls are for their beauty. 

 Indeed, it is the scarcity, and not the beauty 

 of the object, that determines the value of all 

 natural curiosities. Those shells that offer 



but little beauty to the ignorant, are often the 

 most precious ; and those shells which an un- 

 learned spectator would stop to observe with 

 admiration, one accustomed to the visitation 

 of cabinets, would pass over with disdain. 

 These collections, however, have their use: 

 I not only by exhibiting the vast variety of na- 

 ture's operations, but also by exciting our 

 curiosity to the consideration of the animals 

 that form them. A mind that can find inno- 

 cent entertainment in these humble contem- 

 plations is well employed; and, as we say of 

 children, is kept from doing mischief. Al- 

 though there may be nobler occupations 

 than that of considering the convolutions of 

 a shell, yet there may be some who want the 

 ambition to aspire after such arduous pursuits; 

 there may be some unfit for them ; there 

 may be some who find their ambition fully 

 gratified by the praise which the collectors 

 of shells bestow upon each other. Indeed, 

 for a day or two, there is no mind that a 

 cabinet of shells cannot furnish with pleasing 

 employment. " What can be more gratify- 

 ing," as Pliny says," " than to view nature in 

 all her irregularities, and sporting in her 

 variety of shells ! such a difference of colour 

 do they exhibit ! such a difference of figure ! 

 flat, concave, long, lunated, drawn round in 

 a circle, the orbit cut in two ! some are seen 

 with a rising on the back, some smooth, some 

 wrinkled, toothed, streaked, the point vari- 

 ously intorted, the mouth pointing like a dag- 

 ger, folded back, bent inwards ! all these 

 variations, and many more, furnish at once 

 novelty, elegance, and speculation." 



With respect to the figure of shells, Aris- 

 totle has divided them into three kinds: and 

 his method is, of all others, the most con- 

 formable to nature. These are, first, the uni- 

 valve, or turbinated'\v\\\c\\ consist of one piece, 

 like the box of a snail ; secondly, the bivalve, 

 consisting of two pieces, united by a hinge. 

 like an oyster; and, thirdly, the multivawe, 

 consisting of more than two pieces, as the 

 acorn-shell, which has not less than twelve 

 pieces that go to its composition. All these 

 kinds are found in the sea at different depths, 

 arid are valuable in proportion to their 

 scarceness or beauty. 



* Plin. ix. 33. 



