f IS ) 



most important of land animals during the Carbonif- 

 erous period, while the higher Vertebrates were un- 

 known. The later Mesozoic periods saw the reign of 

 reptiles, whose position in structural development has 

 been already stated. Finally, the most perfect, the 

 mammal, came upon the scene, and in his humblest 

 representatives. In Tertiary times mammalia sup- 

 planted the reptiles entirely, and the unspiritual mam- 

 mals now yield to man, the only one of his class in 

 whom the Divine image appears. 



Thus the structural relations, the embryonic charac- 

 ters, and the successive appearance in time of animals 

 coincide. The same is very probably true of plants. 



That the existing state of the geological record of 

 organic types should be regarded as anything but a 

 fragment is, from our stand-point, quite preposterous. 

 And more, it may be assumed with safety that when 

 completed it will furnish us with a series of regular suc- 

 cessions, with but slight and regular interruptions, if 

 any, from the species which represented the simplest 

 beginnings of life at the dawn of creation, to those 

 which have displayed complication and power in later 

 or in the present period. 



For the labors of the paleontologist are daily bring- 

 ing to light structures intermediate between those never 

 before so connected, and thus creating lines of succes- 

 sion where before were only interruptions. Many such 

 instances might be adduced : two may be selected as 

 examples from American paleontology ;* /. e., the near 



* Professor Huxley, in the last anniversary lecture before the 

 Geological Society of London, recalls his opinion, enunciated in 

 1862, that "the positively-ascertained truths of Paleontology" 

 negative " the'doctrines of progressive modification, which suppose 



