BIBLIOGRAPHY. 219 



This second province comprises : — 



I. The Germanic regions extending from the Arctic pro- 

 vince to the hne of the Pyrenees, Cevennes, the Alps, and the 

 Caucasus ; though these mountains seem rather an intercalated 

 territory between the Germanic and Mediterranean regions, 

 than only a common frontier. 



II. The regions of the Mediterranean Lands, compris- 

 ing all the countries along either coast of the Great Sea and the 

 Black Sea, and with Syria, Mesopotamia, and Persia. 



III. The Atlantic Islands, Azores, Madeira, the Canary 

 Islands, the Cape Verde, with perhaps St. Helena. 



As regards both plants and animals, the temperate influence 

 of warmer currents of water and air from the south-west, affects 

 faunal conditions far into the interior of the continent. 



The author discusses at length the commonly-held theory 

 that land-moUusca flourish especially in calcareous districts for 

 the sake of material for their shells, and comes to the con- 

 clusion that land snails prefer, though they do not absolutely 

 require, " uniform, moderate moisture in the ground, without 

 superficial lodgment of water, free access of air and sun, with 

 enough of warm, shady crevices for retreat, and a sufficiency of 

 deeper and easily accessible places for hibernation." The fruit- 

 fulness of limestone districts to the snail hunter probably arises 

 from their yielding these favourable conditions most abundantly. 

 Land mollusca are like plants in their small power of loco- 

 motion, and like plants are apt to. follow local conditions of 

 habitat and development, depending rather on physical peculi- 

 arities of the surface than on the chemical nature of the soil, 

 although a sea-shore soil and its plants have their own fauna. 



A careful disquisition follows upon the occurrence of 

 mollusca in waters of different elevations and different degrees 

 of motion, and (curiously^enough) of different masses of fluids, 

 details and observations which the continental naturalist finds 

 more easily than his British colleague, and the latter will find 

 much interesting matter in this chapter. 



