1867.] LOGAX EOZOOK". 255 



ill both directions. The Wentworth specimens are imbedded in a 

 portion of the Grenville band, which appears to have escaped any- 

 great alteration, and is free from serpentine, though a mixture of 

 serpentine with white crystalline limestone occurs in the band 

 within a mile of the spot. Prom this grey limestone, which has 

 somewhat the aspect of a conglomerate, specimens have been ob- 

 tained resembling some of the figures given by Giimbel in his 

 * Illustrations ' of the forms met with by him in the Laurentian rocks 

 of Bavaria. 



In decalcifying by means of a dilute acid some of the specimens 

 from Cote St. Pierre, placed in his hands in 1864-1865, Dr. Car- 

 penter found that the action of the acid was arrested at certain 

 portions of the skeleton, presenting a yellowish-brown surface ; and 

 he showed me, two or three weeks ago, that in a specimen recently 

 given him, from the same locality, considerable portions of the 

 general form remained undissolved by such an acid. On partially 

 reducing some of these portions to a powder, however, we imme- 

 diately observed effervescence by the dilute acid ; and strong acid 

 produced it without bruising. There is little doubt that these por- 

 tions of the skeleton are partially replaced by dolomite, as more 

 recent fossils are often known to be, of which there is a noted in- 

 stance in the Trenton limestone of Ottawa. But the circumstance 

 is alluded to for the purpose of comparing these dolomitized por- 

 tions of the skeleton with the specimens from Burgess, in which the 

 replacement of the septal layers by dolomite appears to be the 

 general condition. In such of these specimens as have been exa- 

 mined the minute structure seems to be wholly, or almost whoUy, 

 destroyed ; but it is probable that upon a further investigation of 

 the locality some spots will be found to yield specimens in which 

 the calcareous skeleton still exists unreplaced by dolomite ; and I 

 may safely venture to predict that in such specimens the minute 

 structure, in respect both to canals and tubuli, will be found as well 

 preserved as in any of the specimens from Cote St. Pierre. 



It was the general form on weathered surfaces, and its strong 

 resemblance to Stromatopora, which first attracted my attention to 

 Eozoon ; and the persistence of it in two distinct minerals, pyroxene 

 and loganite, emboldened me, in 1857, to place before the Meeting 

 of the ximerican Association for tbe Advancement of Science speci- 

 mens of it as probably a Laurentian fossil. After that, the form 

 was found preserved in a third mineral, serpentine ; and in one of 

 the previous specimens it was then observed to pass continuously 

 through two of the minerals, pyroxene and serpentine. Now we 

 have it imbedded in limestone, just as most fossils are. In every 

 case, with the exception of the Burgess specimens, the general form 

 is composed of carbonate of lime ; and we have good grounds for 

 supposing it was originally so in the Burgess spec^'mens also. If, 

 therefore, with such evidence, and without the minute structure, I 

 was, upon a calculation of chances, disposed to look upon the foim 

 as organic in 1857, much more must I so regard it when the chances 

 have been so much augmented by the subsequent accumulation of 



