bition several years. This habit of hibernation has enabled land snails 

 to be carried many hundred miles from their natural habitat, and has 

 very largely widened the geographical distribution of some species. 



" It is interesting to study the methods by which many species of 

 shells have been carried from one country to another. Land shells may 

 be hidden in fruit, grain, or other merchandise, while the marine snails 

 may become attached to the bottom of vessels, or to the bodies of other 

 animals. The driftwood along the shores of rivers may be carried many 

 hundred miles and thus disperse the mollusks attached to the wood over 

 a large area. Clams have been known to close their shells upon the feet 

 of birds and turtles, and have thus been carried from one pond to another. 

 The most effective method of distribution among the marine snails is by 

 the free swimming larvae, which often swim many miles from their 

 birthplace before settling to the bottom of the sea. 



" The air-breathing snails which we have studied this afternoon," 

 continued Professor Parker, as we left the museum, " are but a limited 

 number of the many thousand species of this very interesting group 

 of animals. Their shells are so easily gathered, and require so little 

 trouble to prepare for the cabinet, that I would advise you all to make 

 a collection of them. If you have no engagement for Monday evening, 

 I should be pleased to have you spend it with me, when we can study 

 the methods of caring for and labeling such a collection." We gladly 

 accepted his invitation, and promised to be at his house at an early hour. 





