384 ANIMAL DEVELOPMENT. 



and, having briefly traced the apparent order in which 

 the advance of organization proceeded, we must direct 

 our few concluding remarks to the physico-physiological 

 influences, which we must confess to know but too 

 imperfectly. 



We learn that, during the states of progress which 

 geology, looking into the arcana of time, has made us 

 acquainted with, a great variety of animal forms were 

 brought into existence. They lived their periods. The 

 conditions of the surface of the earth, the sea, or the 

 atmosphere, were altered ; and, no longer .fitted for the 

 enjoyments of the new life, these races passed away, and 

 others occupied their places, which, in turn, went 

 through all the stages of growth, maturity, and decay ; 

 until at length, the earth being constituted for the 

 abode of the highest order of animals, they were called 

 into existence ; and man, the intellectual monarch of 

 the world, was placed supreme amongst them all. Types 

 of nearly all those forms of life which are found in the 

 fossil state are now in existence ; and if we examine the 

 geographical distribution of animals the zones of 

 elevation over the surface of the earth, and the zones of 

 depth in the ocean, we shall find, now existing, animal 

 creations strikingly analogous to the primitive forms 

 and conditions of the earth's inhabitants. From the 

 depths of the ocean we may even now study as that 

 most indefatigable naturalist, Professor Edward Forbes, 

 lias done the varying states of organization under the 

 circumstances of imperfect light and varying tem- 

 perature.* 



The gradual advance of animal life in the ascending 

 strata has led to many speculations, ingenious and 



* Reports of the Fauna of the &gean : by Professor Forbes. 

 Reports of the British Association. On the Physical Conditions 

 affecting the Distribution of Life in the Sea and the Atmosphere, *c. : 

 by Dr. Williams. Swansea. 



