XXVI INTRODUCTION. 



notice of the latter the above view as being inconsistent with 

 their belief. Doubtless, seeing that this point was not without 

 force, Dr. Hunt, in the paper under notice, has been led to 

 modify his doctrine on the origin of limestones most materially 

 and we feel that some credit is due to ourselves for having 

 contributed to so desirable a result. He now admits that 

 "thousands of feet of limestones have been formed from the 

 calcareous skeletons of marine animals;" also that "the cal- 

 careous rhizopod ' Eozoon Canadense 3 might, and probably did, 

 build up pure limestone beds, like those formed in later times 

 from the ruins of corals and crinoids " ! But he spoils a good 

 thing in stating that our representation of his view of the 

 origin of limestones is a ' ' misconception /' ( ' nor is there any 

 thing inconsistent " in the modified view with his original one ! 

 In speaking of limestones " formed without the intervention of 

 life/' Dr. Hunt refers to none but some " great beds of ancient 

 marble :" these, there can be no doubt, are the te two great 

 formations of limestone beneath the Eozoon horizon, in which 

 this fossil has never been detected. 1 " So it turns out that it is 

 only amongst the pre-" eozoic " Archseans that chemically pre- 

 cipitated limestones are found ! 



1870. Prof. F. Zirkel. Neues Jahrb. f. Mineralogie, 1870, p. 828. 



After describing the roundish grains of serpentine (which are 

 considered to have been originally peridote) occurring in the 

 crystalline limestones (hemithrenes) of Aker, Pargas, Modum 

 (Scandinavia), the author's investigations, it is stated, "did not 

 reveal the canal system which is called eozoonal structure." But 

 it must be mentioned that we have detected in specimens from 

 Aker beautiful examples of " canal system/' 



1870. Eozoon Canadense. T. Mellard Reade. A letter in ' Nature/ 



Dec. 1870, vol. iii. p. 146. 



A considerately-written communication, complaining that the 

 replies to our objections, with few exceptions, " were literally 

 little more than reiterations of previous statements / ; that in 



