J. W. Dawson on Eozoon Canadense. 59 



larly bedded and of great horizontal extent. The Grenville for- 

 mation presents lithological evidences of ordinary atmospheric 

 erosion of the older rocks, and of ordinary aqueous as well as or- 

 ganic deposition. 



Above this is the Norian series of Hunt, or Upper Laurentian 

 of Logan, in which lime-feldspar rocks become dominant, and 

 show that the calcareous rocks accumulated in the preceding 

 period were already contributing to the material of new deposits. 

 No evidence of Eozoon has been found in this series, which is, 

 thus far, entirely unfossiliferous. The Huronian and other series, 

 also of Eozoic or pre-Cambrian rocks, succeed to the Norian, and 

 in one of these, the Hastings group, belonging probably to the 

 Taconian of Hunt, specimens of Eozoon and indications of worm- 

 burrows and other obscure fossils have been found. 



With reference to the mode of preservation of Eozoon, it was 

 stated that in its ordinary condition, as mineralised by serpen- 

 tine, it presents the simplest kind of mineralisation of a calcareous 

 fossil ; that in which the orignal calcite walls still exist, with no 

 change except a crystallisation of the calcite, common in the fossils 

 of newer formations, and with the cavities filled with a hydrous 

 silicate, which was evidently in process of deposition on the sea- 

 bottom on which Eozoon is supposed to have lived. Commencing 

 with this fact, the author proceeded to show that the various im- 

 perfections and accidents of preservation observed in Eozoon are 

 precisely parallel to those observed in palaeozoic and mesozoic 

 fossils. 



In conclusion, it was stated that many new observations had 

 been made by Dr. Carpenter and the author, and would appear 

 in a memoir now in course of preparation by the former, and that 

 the author hoped, on the occasion of the visit of the British Asso- 

 ciation to Canada next year, to exhibit to those interested in the 

 subject the large series of specimens of Eozoon now in the mu- 

 seum of McGrill University. 



