376 



Ohio Shells. 



spacious, for the contrary reason ; and where all the varied forms 

 have grown out of the indispensable wants, the abilities and 

 taste of the inhabitants, whether these have been acquired in 

 America, Europe, or in China. Decorticated beaks would not be 

 wanting ; yet Chesnut and Arch streets — those Miami's of houses 

 —-would furnish abundant exceptions ; and then as to cornutus, 

 horns, as long as chimneys were standing, would not be wanting, 

 long or short. In regard to the unio cornutus, it fares no better 

 in the hands of Messrs. Short and Eaton, than unio cariosus. 

 They remark on this shell, to which they have assigned pro- 

 fessor Rafinesque's original name of unio torulosus : " all pos- 

 sible varieties of this heteramorphous shell were found in the 

 Ohio: the unio foliatus of Hildreth, which Mr. Lea thinks nothing 

 more than a variety of the unio cornutus of Barnes, was found, 

 and among our numerous specimens of this variety, not one had 

 hardly the rudiment of a horn.^"* 



Here we have horned shells without horns, as we before had 

 carious shells perfectly sound. What would be said of the want 

 of sense of cattle breeders, if they were to talk of long horned 

 cattle with no horns, and Durham short horns with long horns. 

 These practical men know that the Durham short horn, and the 

 Bakewell breed of sheep, both of which, externally, differ from 

 all other animals of the same races, are artificial varieties pro- 

 duced by particular treatment ; but that if the circumstances to 

 which the varieties were owing, no longer influenced them, the 

 varieties would disappear. We have seen that the same shell 

 can differ greatly in its shape ; that it is sound in one river, and 

 carious in another. W^hat the particular causes of such carious- 

 ness are, we know not at present ; but we do know that mollusca 

 repair their own shells when injured, and may infer that the 

 degree of intelligence requisite for that act, may govern the 

 young mollusca in modifying the primary form of its shell, ac- 

 cording to the exigences of the circumstances which surround 

 it ; and that when it is much varied, it is but evidence of what 

 the animal is capable of doing for conservative purposes. 



When conchologists study the animals more, and the shells 

 less, or rather when they consider the animals themselves as the 

 proper objects of study, every accession to our knowledge of this 

 branch, can be carried to the general account of natural history, 

 to the honour of the discoverer. Writers who contend for priority 



