602 Sir W. Daicson — The Animal Nature of Eozoon, 



has been the principal agent in producing the secondary 

 metamorpbism/ and we think with the latter that the association 

 of the diamond with a peridotite is not fortuitous, though we believe 

 that this mineral, like the others mentioned above, originated at 

 a much greater depth in the earth's crust. This view, we were glad 

 to find, had already commended itself to Prof. Daubree, who makes 

 some highly suggestive remarks on the association of diamonds and 

 meteorites.'^ 



III. — Eeview of the Evidence for the Animal Nature of Eozoon 



Canadense. 



By Sir William Dawson, C.M.G., LL.D., F.R.S., etc. 



II. Petrological and Chemical. 



BEAEING in mind the statements made in the previous note, 

 respecting the stratigraphical relations of the Grenville Series, 

 and referring to the excellent account by my friend Dr. Bonney 

 of his observations at Cote St. Pierre, and to some difficulties stated 

 bj' him which merit attention, we may sum up the evidence so far, 

 under the following statements : — 



1. The limestones included in the Grenville Series and their 

 associated quartzites and schists bear so strong a resemblance in 

 mineral character to metamorphosed Palaeozoic calcareous beds of 

 organic origin and their associates, as to warrant at least the careful 

 consideration of any forms apparently organic contained in these 

 limestones. 



2. The occurrence in these limestones of nodular silicates, of 

 graphite, of pyrite, and of apatite, affords additional reason to 

 suspect their organic origin. 



3. The presence of large beds as well as of veins of graphite 

 and of thick deposits of iron ore in the Grenville Series constitutes 

 an additional analogy with Palaiozoic formations holding organic 

 remains.^ 



These facts were adduced by Dr. Sterry Hunt and Dr. J. D. 

 Dana in evidence of the probability of life in the Laurentian period, 

 even before the discovery of Eozoon. Certain particulars connected 

 with them, however, now demand somewhat more detailed attention, 

 in connection with that discovery, and with recent objections to the 

 organic nature of Eozoon. 



Dolomite or magnesian limestone is a not infrequent associate of 

 Palseozoic fossiliferous limestones; and I have remarked in previous 



metamorphism of the carbonaceous material in the shales. — Q.J.G.S., vol. xxx, 

 1874, p. 64; vol. xxxiii, 1877, p. 879; vol. xxxvii, 1881, p. 609. Prof. Green 

 informs us that his examination led him to the conclusion that the 'pipes' were 

 volcanic necks. 



' This may have been the last stage in a series of volcanic disturbances, of which 

 the flows noticed by Prof. Green {loc. cit.) may have been the earliest. 



2 Loc. cit., pp. 20-24. Prof. Lewis had already called attention to certain points 

 of likeness in the diamantiferous rock and meteorites. 



^ See papers by the author on the Graphite and Phosphates of the Laurentian 

 Eocks, Quart. Journ. Geol. Soc. London, 1869 and 1876. 



