STEATIGEAPI-IICAL GEOLOGY. 19 



pearance in the Devonian seas. During all this time, the earth was barren and 

 lifeless. Mighty changes had taken place, mud had been deposited on the bed 

 of the ocean many miles in thickness, and life had grown from its mineral origin 

 in the ocean, nntil it had nearly the strength to maintain itself on land; but all 

 this had been accomplished as si]entl_y as the earth moves in her orbit. The 

 same gradual development continued throughout each sub-kingdom to the close 

 of the Carboniferous period. The evolution in animal forms was as slow as time, 

 and quite as monotonous, except in the constant progi-oss to a higher and more 

 complicated existence. The Coal Measures furnish us with lish-like remains, 

 having the limbs of a frog or the breathing capacity of a tailed batrachian. 

 Several genera have been made from the fossil remains of this period, which 

 bridge the chasm, from tlie Ganoid fish to the batracliian and the lacertian. The 

 highest I'iilffiozoic type of animal life, yet known. Prof Dawson has called 

 Hylonomus lyelli. The distinguished principal nI'Mi'Gill College says, that it pre- 

 sents characters partly allying it to the newts and other batrachians and partly 

 to the true lizards. The structure of the skull and vertebriB resembling a 

 batrachian, and the well develoix'd ribs, broad pelvis, and cutaneous covering 

 assimilating it to the true lizards. 



The following inferences are therefore to be drawn from the testimony af- 

 ford.ed by the Pah\;ozoic rocks: 



First. That the maximum thickness of the Groups of strata is from twen- 

 ty-live to thirtj' miles. 



Second. That it required many millions uf years for the formation of these 

 Groups. 



Third. That both vegetable and animal life commenced an existence, in 

 the lowest forms, such as might have been produced by a concentration of chemi- 

 cal forces, or, by what has been called spontaneous generation. 



Fourth. That, by processes of evolution, vegetable life developed from 

 marine forms to land plants. 



Fifth. That animal life began in the sub-kingdom Protista; from this sub- 

 kingdom, by processes of evolution and the survival of the fittest, there arose 

 Eadiates, MoUusks, Articulates and Vertebrates. Each of these sub-kingdoms 

 is now in the highest state of its development, though many families and some 

 orders in each sub-kingdom have had their day and become extinct, or have been 

 on the decline for untold ages. 



