THE BEGINNING OF LIFE ON THE EARTH. 41 



descendants one of the other, we have no absolutely certain 

 information to give. On the one hand, it is not inconceivable 

 that such forms as Stromatopora or Nummulina may have de- 

 scended from Eozoon. On the other hand, it is equally con- 

 ceivable that the same power which produced Eozoon at first, 

 whether from dead matter or from some unk^- own lower form 



Fig. 27. — Foraminiftral Rock Builders, in the Cretaceous and Eocene. 



a, Ntimniulites iarvi^ata—Koceue. b. The same, showing chambered interirr. c, 

 MilioUne hmestone, magnified— Eocene, Pans, d, Hard Chalk, section magnitied— 

 Cretaceous. 



of life, may have repeated the process in later times with 

 modifications. In any case it is probable that the Foraminifera 

 have experienced alternations v ' expansion and shrinkage, of 

 elevation and decadence, in the lapse of geological time. 

 There were times in which many new forms swarmed into ex- 

 istence, and times in which old forms were becoming extinct 



