198 THE DISPERSAL OF SHELLS. 



abundant along the promenade at Southport^ and only 

 observed there in recent years, is " supposed to have 

 been imported with the building materials," ' and the 

 same species, to give another case, established in gar- 

 dens, now disused and weed-grown, around some of 

 the Martello Towers in the midst of the broad shingle- 

 beach, which, of course, is destitute of terrestrial mol- 

 luscs, between Eastbourne and Hastings was probably 

 introduced, Mr. Pearce suggests, with the chalky soil 

 of which the little plats were formed, or it may have 

 been carried thither with garden plants. 



That the creatures have been widely dispersed along 

 with plants, shrubs, etc., now so frequently sent from one 

 country to another, cannot be doubted for a moment ; 

 unconsciously horticulturists have probably done more 

 than any other class of persons to mix the aboriginal 

 faunas of distant countries, and doubtless transportal in 

 this way for short distances is constantly taking place. 

 Wardian cases, as Mr. Layard remarks to me, must 

 certainly be great factors of dispersal, and living snails 

 are known to have been transported with quite small 

 consignments of plants, in the earth at their roots, 

 and even with " dry-bulbs " transmitted with little or no 

 earthy matter. Foreign snails, and others evidently 

 from a distance, are \^ell known to turn up every now 

 and then in greenhouses : during 1883, Mr. Musson pro- 

 cured three foreign species, probably South American, 



' H. H. Higgins, " Address to Liverpool Nat. Field Club, January 

 30th, 1 891," p. 24 ; the creature occurs also near Southport at 

 Moels Cop Road. 



