WILD LIFE OF ORCHARD AND FIELD 



influences make long-separated islands more pro- 

 ductive of mollusks than are continents, and at 

 the same time deficient in enemies to snails. 



How has this curious distribution come to pass? 

 How have seemingly impassable barriers been 

 overcome, so that closely related forms are now 

 found at the antipodes? 



Snails are of domestic tastes. "The heathen 

 painted before the modest women's doors Venus sit- 

 ting upon a snail, quae domi forta vacatur, called a 

 house-bearer, to teach them to stay at home and to 

 carry their houses about with them. " They are also 

 slow of pace, as a list of poets are ready to stand up 

 and testify ; but they have had a long time in which 

 to ''get a good ready,'' first to start, and afterwards 

 to accomplish their travels, since their existence 

 as a race goes back to when dark forests of ferns 

 waved their heavy fronds over the inky palaeozoic 

 bogs. Distance disappears in the presence of such 

 prodigious time. Lands like our Western plains, 

 now an arid waste impassable to mollusks, were 

 clothed in bygone ages with dense and limitless 

 verdure, where every form of terrestrial life abound- 

 ed. Between the present and the time of the lay- 

 ing down of those sandstones that make the soil 

 of our level plains, the Rocky Mountains have 



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