509 



curring in micro -crystalline calcite; and that the " nummuUne layer? 

 coating the serpentine granules, is a film of chrysotile in various states 

 of modification. Metaxite and chrysotile we showed to be mere alio- 

 morphs of serpentine, being the same hydro-magnesian silicate, under 

 other forms besides the amorphous, that characterizes the latter : the 

 three correspond to the fibrous, branching, and amorphous varieties 

 not unusual to calcareous, siliceous, and some other minerals. 



Moreover, " eozoonal" structures were shown to have never leen 

 found except in crystalline or metamorphic rocks, especially those contain- 

 ing serpentine, or some of its varieties ; and to occur under these 

 conditions in deposits of widely different geological ages — not only in 

 the Laurentians, but in others that are members of later systemal pe- 

 riods, even in the serpentine or crystalline marbles belonging to the 

 Liassic system. 



The " fossil" we are engaged with has obtained sufficient notoriety 

 as a disputed body, and it is of so much importance in geology, irre- 

 spective of whatever view may be taken of it, as to require from all 

 who are interested in the truthful progress of this science extremely 

 careful consideration, and the most searching investigation. Yet the 

 late President of the Geological Society, Mr. Wamngton W. Smyth — 

 who declared that " the grandest feat of geological science within the 

 last few years is the astounding extension of the scale of geological 

 time consequent on the discovery of ' Eozoon Canadense' " — has set 

 aside a "fact" of considerable weight for a mere unsupported an- 

 nouncement. " The elaborate arguments of Messrs. King and Rowney 

 in favour of the mineral origin of ' eozoonal' structure had at one 

 time a strong show of support in the fact that these appearances" (struc- 

 tures) " were always observed in serpentinous limestone (ophicalcite) 

 only, whether in Canada, Connemara, Tyree, Bavaria (Dr. Giimbel), 

 or Bohemia (Dr. Yon Hochstetter), notwithstanding great discre- 

 pancy in the age of some of the deposits. But the announcement made 

 by Dr. Carpenter in the ' Quarterly Journal of the Geological Society 

 for August last (1865),' of Dr. Dawson's discovery of ' Eo%oon' pre- 

 served in carbonate of lime pure and simple, would appear to close the 

 discussion."* 



In the present communication it is our intention to review all the 

 arguments and evidences, including statements made in connexion with 

 the above announcement, that have been brought forward since our 

 Paper was published ; and we shall adduce additional proofs against 

 what Dr. Carpenter calls the " received doctrine." Moreover, Conne- 

 mara abounds with rocks yielding some of the most beautiful marbles 

 known, and composed to a considerable extent of " Eozoon Canadense" — 

 a fact which may be held of additional importance in inducing the Royal 

 Irish Academy to take a part in promoting the settlement of the 

 question as to the origin of this so-called " fossil." 



* Anniversary Address to the Geological Society. See " Quarterly Journal of Geo- 

 logical Society," vol. xxiii., p. lxiv. 



