222 THE DISPERSAL OF SHELLS. 



Mr. Rogers thought it likely that they might pass the 

 blowing process undamaged. This view of the creature's 

 introduction was questioned, however, by Mr. Anthony, 

 an eminent American conchologist, who was of opinion 

 that the species did not inhabit the cotton-growing 

 states. But Mr. Rogers further suggested that the 

 shells might have attached themselves to submerged 

 cotton used for defensive purposes — as barricades for 

 steam-boats or river defences — during the war between 

 the North and South, and that it might have been trans- 

 ported to this country during the cotton famine brought 

 about by the war, when Lancashire people, it is said, 

 were glad to get material in any condition, wet or dry, 

 blockade-run, or otherwise ; and this theory seems to 

 have been generally accepted by British concho- 

 logists. The animal seems to have multiplied consider- 

 ably in its new home : a few years after its discovery, 

 when one of the canals was run dry for repairs, Mr. 

 Rogers saw it, in countless numbers, extending about a 

 mile from where it originally occurred ; unfortunately, 

 however, nearly all these vast numbers were killed when 

 the brickwork of the waterway was repointed with 

 mortar containing a good quantity of lime. In the 

 Conchological Society's list the name of the species was 

 enclosed in brackets^ in order to denote that its 

 claim to rank as British was not considered to be 

 thoroughly established ; but Mr. Collier, of Manchester, 

 commenting on this in 1884, expressed the opinion that 

 the creature might be regarded as fully naturalized, and 

 the brackets have been removed, I find, in a new edition 



