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SPREADING OF THE AMPHIBIA. 



The Amphibia of the Torrid Zone are the largest, 

 the most frightful, and the most numerous. In the 

 Temperate Zone they become smaller, and less nu- 

 merous ; and cease altogether at the Frigid Zone. 



1. Of all Amphibia, Frogs and Toads are most 

 numerous in the colder portion of the Temperate 

 Zone ; and are found in the Northern Hemisphere, 

 between the 50th and 60th degrees of latitude, in 

 greater number than Snakes and Lizards. Although 

 the largest species of this Genus are natives of the 

 Warm Zone, as the Argus Frog (Rana occellata) in 

 the warmer part of America; yet they seem to 

 be particularly common to the Temperate Zone. 

 How near they approach to the snow-line cannot 

 be ascertained ; but, as they grow stiff by cold, 

 their native country cannot be in the neighbour- 

 hood of the snow-line. In Greenland there are 

 neither Frogs nor Toads. The Green Frog (R. 

 esculentd) is met with in Lapland ; and the Brown 

 Frog in most European countries. As these ani- 

 mals, when transformed from water-breathing fish 

 to air-breathing animals, gain a more perfect life 

 than fish have, they may extend farther towards the 

 snow-line than fish which inhabit fresh water. In 



