THE PLAINS AND COLORADO 133 



ones known ; and hence the present generation is 

 contemporary with the termination of a given kind 

 of bird. 



Now, there are many other kinds of sea-ducks 

 of similar migratory habits to the one under con- 

 sideration, notably the different species of eider- 

 duck, and the various birds classed under the 

 head of surf-ducks or coots, not to mention the 

 old squaws, the golden eye, and their allies. It 

 therefore does not seem probable that by any in- 

 fluence exerted by men, and certainly not the 

 efforts of game- and pot-hunters, was the extermi- 

 nation of this species accomplished. Such a 

 result must be inevitable to aggregations of indi- 

 viduals of a given kind to which we apply the 

 term " species." They have their beginning, their 

 rise and culmination, and their end, much as is 

 the case with nations, to which they may be 

 likened. The point which I wish to emphasize 

 here is that the process of organic evolution is 

 not something of the past ; the present period is 

 as much concerned with it as any, and the above 

 facts are recited to show that, under our very 

 eyes, something that most of us look upon as a 

 remote force, which had its chief action in the 

 early history of the world, is still potent, and 

 carries on its work now. In short, species origi- 

 nate and disappear to-day just as they have always 

 done. I said "originate," and I shall presently, 



