GEOGRAPHICAL DISTRIBUTION OF ANIMALS 989 
have developed almost independently of one another. ‘To 
the fresh-water fishes the sea forms equally a barrier, and 
(Permission of 
Photograph by Dr. R. T, Morris. 
G. O. Shields, publisher of Recreation. 
Fig. 175.—A Labrador salmon clearing an 18-foot waterfall. 
even the shore-fishes very rarely pass across great depths. 
Relatively few of the shore-fishes of Cuba, for example, ever 
cross the deep Florida Straits, and none of those of Cali- 
20 
