CHAPTER VII. 



CONCLUDING REMARKS. 



IN the preceding chapters we have obtained a glimpse 



and only a glimpse of the Animal Kingdom as it 

 now appears on the surface of our globe. But the animals 

 of the present, vast as are their numbers, are but a hand- 

 ful compared to those that have occupied the surface of 

 the earth in past geologic ages, and that are now known 

 only by their petrified remains, which fill the rocks in 

 many countries to the depth of six or eight miles or more. 

 Nature has embalmed these races, and handed them 

 down to us so perfectly preserved, that we are able to get 

 at least a faint view of the phases of life during all the 

 past ages of the world. And it is a fact of the highest sig- 

 nificance, that all the animals of the past, and all those of 

 the present, are created according to the same great plan. 

 Radiates, Mollusks, Articulates, and Vertebrates are the 

 four* Types under which animal life has been exhibited 



* We must not omit to mention, that there is a vast number of beings 



regarded by some as animals and others as plants which are believed 



Fig. 529. 



Fig 530. Fig. 531. Fig. 532. 



ml 

 ^S? 



Gregarina sipunculi. 



Portion of 5". punctatum, 

 Sphtzrozmtm punc- magnified. 



ttitiitn. 



Vorticclla. 



Figs. 529-539. Protozoa. 



