V. 



Eozoon and the Monte Somna Blocks. 



IN consequence of the Note in our February number, entitled 

 " Eozoon : Requiescat in Pace," as well as our remarks on the 

 letter written to us by Sir William Dawson and printed on p. 288, 

 we have received several more letters from Sir William, strongly 

 protesting against the re-burial of Eozoon. He has also enclosed a 

 criticism on what he calls " the strange mis-statements " contained 

 in the paper on " Eozoonal Structure of the Ejected Blocks of Monte 

 Somna," by Drs. Johnston-Lavis and Gregory {Trans. R. Dublin 

 Soc, vol. v., ser. 2). In consequence of the great interest that has 

 been aroused by this paper, we print Sir William's criticism in full, 

 together with a short reply by Drs. Johnston-Lavis and Gregory. 



I desire to make a few remarks on the paper by Dr. Johnston- 

 Lavis and Dr. J. W. Gregory, not for the purpose of entering into 

 the general questions relating to the organic structure of Eozoon, but 

 to indicate certain reasons for the belief that the appearances 

 described in the paper have no relation to Eozoon canadcnse, either in 

 mode of occurrence and mineral character or in microscopic structure, 

 and consequently that, whatever the interest and value of the paper 

 in other connections, the references to the Laurentian fossil are 

 wholly gratuitous and unnecessary, while they are also in very 

 important respects incorrect. 



In making these criticisms I shall, for the sake of simplicity, 

 refer only to those typical specimens of Eozoon in which the laminae 

 remain as calcite, while the chambers are filled with serpentine or 

 more rarely with malacolite, and the canals and tubuli with serpentine 

 or dolomite. 



1. Mode of Occurrence and Mineral Character. — The paper states in 

 three distinct places that the typical Eozoon is enclosed in a pyroxenic 

 igneous rock, as follows : — 



Page 260. " The typical Eozoonal nodules occur enclosed in a 

 rock of which a white pyroxene is the leading constituent." 



Page 275. " Concentric Eozoonal masses are included in a 

 coarse-grained rock which is composed of white pyroxene, and which, 

 therefore, may safely be regarded as igneous in origin." 



Page 277. " The Cote St. Pierre spheroids (of Eozoon) are 

 probably cases of blocks included in either a volcanic or plutonic 

 mass." 



