THE CARP POND. 145 



show certain very special modifications, 

 adapted to their peculiar mode of life, but 

 they are also comparatively cosmopolitan in 

 their tastes, being able to enter the sea, to 

 which some species have taken permanently, 

 though still keeping for the most part to 

 shallow muddy bottoms. As they are thus 

 but little deterred by intervening oceans, they 

 were enabled to spread rapidly over the whole 

 of the tropics, reaching Northern Australia 

 from India, and even crossing from South 

 America to the Sandwich Islands. As yet, 

 however, they have not made their way into 

 the coral islands of the Pacific. Northward 

 they spread far more slowly, as they are no 

 lovers of cold water. Only one species has 

 penetrated into Europe, and but few into 

 temperate Asia. The North American 

 kinds, though more numerous, belong all to 

 a single group. Towards the south temperate 

 regions, where the land tapers slowly south- 

 ward, they spread slowest of all ; so that the 

 family is entirely wanting in Tasmania, New 



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