294 AIR-BREATHERS OF THE COAL PERIOD. 



necessary to hare recourse to that which supposes at particular 

 periods a sudden; and as yet unaccountable transmutation of one 

 form into another; a view which in its remoteness from anything 

 included under ordinary natural laws, does not materially diner 

 from that currently received idea of creative intervention, with 

 which, in so far as our coal reptiles can inform us, we are for 

 the present satisfied. 



There is one other point which strikes the naturalist in consid- 

 ering these animals, and which has a certain bearing on such hy- 

 pothesis. It is the combination of various grades of reptilian types 

 in these ancient creatures. It has been well remarked by Hugh 

 Miller, and more fully by Agassiz, that this is characteristic of 

 the first appearance of new groups of animals. Now selection, 

 as it acts in the hands of the breeder, tends to specialization ; and 

 natural selection, if there is such a thing, is supposed to tend in 

 the same direction. But when some distinctly new form is to be 

 introduced, an opposite tendency seems to prevail, a sort of aggre- 

 gation in one species of characters afterward to be separated and 

 manifested in distinct groups of creatures. The introduction of 

 such new types also tends to degrade and deprive of their higher 

 properties previously existing groups of lower rank. It is easy 

 to perceive in all this, law and order in that higher sense in which 

 these terms express the will and plan of the Supreme Mind, but 

 not in that lower sense in which they represent the insensate 

 operation of blind natural forces. 



Humble though the subjects of this paper are, we see in them 

 the work of Supreme Intelligence, introducing new types 

 upon the scene and foreshadowing in them those higher forms 

 afterward to be created. It is this, their Divine origin, and the 

 light which they throw on the plan and order of the creative 

 work, of which we ourselves form a part, that gives them all 

 their interest to us. They are the handiwork of our Father and 

 our God, traces of his presence in primeval ages of the earth, 

 evidences of the unity of his plan and pledges of its progressive 

 nature ; adding their feeble voices to the testimony of revelation 

 in respect to the history of creation in its earlier stages, and to 

 the carrying on of that plan which still involves the extinction of 

 many things from the present world, and the elevation of others 

 into new and glorious manifestations. Their place in the system 

 of nature and in the order of the world's progress, their uses in 

 their own time and their relations to other beings as parts of the 



