266 HISTORICAL GEOLOGY. 



of life. Limestone, as we have seen (pages 114-117), is 

 now, and at previous geological times, usually, though not 

 always, of organic origin. 



Judging from these signs, it would seem that life was 

 not only present, but in large quantity. Can we say any- 

 thing as to its kind ? Are there any fossils ? Here we 

 must answer still more doubtfully. Some curious forms 

 are found which are supposed to be those of the lowest 

 order of animals (compound Protozoa). These have been 

 called eozoon or dawn-animal, and therefore some have 

 called this first era eozoic. Most, however, do not accept 

 this animal, and prefer the name Azoic (no animal life), 

 or, better still, Archaean or Archaeozoic, as carrying no 

 implication. 



In conclusion, we may say that the existence of the 

 lowest forms of vegetable life is almost certain, and of 

 the lowest forms of animal life probable. 



