ITS FAUNA. 51 



ence by a life of ceaseless activity and toil, others are formed 

 for parasitic attachment to the living tissues of larger 

 animals, and there find life and enjoyment without a single 

 effort or care of their own. And as these varied functions 

 necessarily require for their performance a special adapta- 

 tion of organs a tooth to cut or a tooth to grind, a foot to 

 seize or a foot to dig, a limb to run or a limb to fly so 

 will similar modifications afford to the palaeontologist an 

 evidence of functions performed in bygone ages, and enable 

 him, not only to reconstruct forms of harmonious organs, 

 but to assign to these organs the part they had to play in 

 the great drama of vitality. In the performance of these 

 varied functions many animals have to make long periodic 

 migrations, either for the immediate purpose of procuring 

 food and shelter for themselves, or prospectively for their 

 future young. From colder to warmer regions, and from 

 warmer to colder from land to water, and from water to 

 land from sea to river, and from river to sea there is 

 ever, among certain animals, an incessant interchange; and 

 though palaeontology has yet been unable to detect such 

 migrations in the past, we may rely on their occurrence, 

 and be prepared to admit the fact into our inferences and 

 reasonings. 



Coexistent with and beyond all this, there are those in- 

 numerable differences of species and kind and family and 

 class, which we can only resolve into the eternal will of the 

 Creator. Why, for instance, should the polype differ from 

 the star-fish, the star-fish from the crab, the crab from the 

 turtle, the turtle from the fish, the fish from the bird, or 

 the bird from the quadruped 1 It is in vain to tell us that 

 the one is but a progressive or developmental form of the 

 other that the reptile is but a transmutation, in time and 

 under new external conditions, from the fish, and that the 

 fish is but the lineal descendant o the shell-fish. Adniit- 



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