CHAPTER VII. 

 THE BLUFF AND THE CAT-TAILS. 



"QEFORE studying the matter, it would not occur to one 

 -L) how different the plants and animals are the world over. 

 Each individual has its particular locality or habitat. 

 Sometimes, as in the case of certain species of Humming- 

 birds, that habitat is a single island or mountain; again, as 

 in the case of the Duck Hawk or Osprey, it is, in its various 

 allied forms, nearly or quite cosmopolitical. Generally, 

 however, great mountains and seas or changes of climate 

 .bound these habitats. For instance, in Eastern North 

 America we have a certain set of birds, extending from the 

 Atlantic Coast westward to the Rocky Mountains; but from 

 this great mountain system, running north and south the 

 entire length of the continent, to the Pacific Coast, there 

 is found another set, generally more or less allied to ours 

 indeed, but for the most part specifically different. Again, 

 we have certain species peculiar to the northern, and others 

 peculiar to the southern, latitudes ; and between the plants 

 and animals of the several continents the difference is gener- 

 ally very great. What is true of space, in this respect, is still 

 truer of time. In respect to the fauna of the various geological 

 ages, the differentiation is indeed immense. But all these 

 vast varieties of form are built on certain fixed plans of 

 structure. The great classes, orders, and families have 

 their representatives everywhere; and, while these types of 



