14 TfiE CANADIAN NATURALIST. [March 



bility of this on various grounds^'^ ; and my object in referring to 

 these indications in 1864, as well as to the supposed burrows of 

 annelids, subsequently described by me f, was to show that the 

 occurrence of Eozoon was not to be regarded as altogether isolated 

 and unsupported by probabilities of the existence of organic 

 remains in the Laurentian, deducible from other considerations. 



Now that the questions which have been raised regarding 

 Eozoon may be considered settled, not only by the adhesion of 

 the greatest authorities in palaeontology and zoology, but by the 

 discovery of similar organisms in rocks of the same age elsewhere, 

 by specimens preserved in such a manner as to avoid all the 

 objections raised to the mineral condition of the fossil J, and by 

 the discovery of such modern analogies as that furnished by 

 Batliyhius, it may be proper to invite the attention of geologists 

 more particularly to the evidence of vegetable life afforded by the 

 deposits of graphite existing in the Laurentian. 



The graphite of the Laurentian of Canada occurs both in beds 

 and in veins, and in such al^nanner as to show that its origin and 

 deposition are contemporaneous with those of the containing 

 rock. Dr. Sterry Hunt states § that " the deposits of plumbago 

 generally occur in the limestones or in their immediate vicinity, 

 and granular varieties of the rock often contain large crystalline 

 plates of plumbago. At other times this mineral is so finely 

 disseminated as to give a bluish-gray colour to the limestone, and 

 the distribution of bands thus coloured, seems to mark the strati- 

 fication of the rock." He further states : — " The plumbago is 

 not confined to the limestone ; large crystalline scales of it are 

 occasionally disseminated in pyroxene rock or pyrallolite, and 



Geol. Society, 1859, p. 493, Amer. Jour. Science, July 1860 (xxx., 134, 

 as well as in the last-named Journal for May 1866, as quoted above. — 

 J. W. D. 



*■ Manual of Geology. I may also be permitted to refer to my own 

 work " Archaia," p. 168, and Appendix D, 1860. 



t Quart. Journ. Geol. Soc. vol. xxii. p. 608. 



X I cannot, after examination of the specimen, and of others subse- 

 quently obtained by Sir "W. E. Logan, attach any value to the supposition 

 of Messrs. Rowney and King, that the Tudor specimen has been produced 

 by infiltration of carbonate of lime into veins. The mechanical arrange- 

 ment of the laminae and their microscopic structure forbid such a 

 supposition, as well as the comparison of them with the actual calcare- 

 ous veins occurring in the same rock. 



§ " Geology of Canada," 1863, p, 529 ; and Report for 1866, pp. 218-223. 



