286 On the Structure and Position of Eozoon Oanadense. 



the Lower Laurentian strata were in process of formation. 

 The needed proof has been supplied, however, by the discovery 

 of the very remarkable fossil which it is my special object to 

 describe; the JEozoon Oanadense thus taking rank as by far the 

 earliest form of animal life yet known, its development 

 having been antecedent to the deposition of the greater part 

 of the Laurentian series, nearly the whole thickness of which, 

 with the Huronian in addition — amounting, as we have seen, 

 in Canada to nearly 50,000 feet, and in Central Europe to 

 90,000 — had been superimposed upon the lowest beds in which 

 it occurs, before the epoch of the Lingula flags, which once, in 

 the opinion of many geological authorities, marked the first 

 appearance of life on our planet. 



The history of this discovery is in itself not a little 

 curious. Certain bodies presenting forms apparently organic 

 were brought by Mr. J. McCulloch to Sir Wm. Logan, in 1858, 

 from the Grand Calumet limestone on the river Ottawa; and these 

 were found to be composed of alternating parallel or some- 

 what concentric layers of crystallized pyroxene and carbonate 

 of lime. This alternation called to mind other specimens 

 exhibiting a similar structure, which had some years pre- 

 viously been obtained, by Br. "Wilson, of Perth, from the 

 Burgess limestone, but which had been regarded merely as 

 minerals ; their forms were the same as those of the Grand 

 Calumet specimens, but their composition was different, the 

 alternating layers being formed of Loganite (dark green 

 silicate of magnesia) and Dolomite (magnesian limestone). 

 Thus in both cases the alternation, though formed by different 

 minerals, always consisted of siliceous and calcareous layers ; and 

 hence Sir William Logan, thinking it strange that identical 

 forms should be derived from minerals of such different 

 composition, was led to look upon them as fossils. As such 

 they were exhibited by him at the meeting of the American 

 Association for the Advancement of Science in 1859 ; and 

 they were shown to some of his geological friends on this 

 side of the Atlantic in 1862. One of the specimens had been 

 sliced and submitted to microscopic examination; but 

 unfortunately it was one of those composed of Loganite and 

 Dolomite, in which minute structure rarely occurs ; and in 

 the absence of any evidence from this source, few except Pro- 

 fessor Ramsay seemed disposed to believe in their organic nature. 



The true character of these bodies thus remained in 

 suspense until a little more than twelve months ago, when Sir 

 Wm. Logan observed indications of similar forms in blocks of 

 the Laurentian limestone from the Grenville bed, which is the 

 highest of the three zones of limestone occurring in the Lower 

 Laurentian series, and which attains, in some places, a 



