OPPONENTS AND OBJECTIONS. 193 



accounting for fossils would not be tolerated for a moment, 

 were it not for the great antiquity and highly crystalline con- 

 dition of the rocks in which the structures are found, which 

 naturally create a prejudice against the idea of their being 

 fossiliferous. That the authors themselves feel this is apparent 

 from the slight manner in which they state the leading facts 

 above given, and from their evident anxiety to restrict the 

 question to the mode of occurrence of serpentine in limestone, 

 and to ignore the specimens of Eozoon preserved under 

 different mineral conditions. 



2. With reference to the general form of Eozoon and its 

 structure on the large scale, I would call attention to two 

 admissions of the authors of the paper, which appear to me to 

 be fatal to their case : — First, they admit, at page 633 [Pi'o- 

 ceedings, vol. x.], their " inability to explain satisfactorily " 

 the alternating layers of carbonate of lime and other minerals 

 in the typical specimens of Canadian Eozoon. They make a 

 feeble attempt to establish an analogy between this and 

 certain concentric concretionary layers ; but the cases are 

 clearly not parallel, and the laminaa of the Canadian Eozoon 

 present connecting plates and columns not explicable on any 

 concretionary hypothesis. If, however, they are unable to 

 explain the lamellar structure alone, as it appeared to Logan 

 in 1859, is it not rash to attempt to explain it away now, when 

 certain minute internal structures, corresponding to what 

 might have been expected on the hypothesis of its organic 

 origin, are added to it ? If I affirm that a certain mass is the 

 trank of a fossil tree, and another asserts that it is a concretion, 

 but professes to be unable to account for its form and its rings 

 of growth, surely his case becomes very weak after I have 

 made a slice of it, and have shown that it retains the structure 

 of wood. 



Next, they appear to admit that if specimens occur wholly 

 composed of carbonate of lime, their theory will fall to the 

 ground. Now such specimens do exist. They treat the Tudor 

 specimen with scepticism as probably " strings of segregated 

 calcite." Since the account of that specimen was published, 

 additional fragments have been collected, so that new slices 



O 



