76 Geological Society. 



into two unconformable groups, which have been called the Upper 

 and Lower Laurentian respectively. In both divisions zones of 

 limestone are known to occur, and of them at least three have 

 been ascertained to belong to the Lower Laurentian. From one of 

 these limestone-bands, occurring at the Grand Calumet on the River 

 Ottawa, Mr. J. McCulloch obtained, in 1858, specimens apparently 

 of organic origin, which were exhibited as such by the author in 

 1859 ; and other specimens have also been obtained from Grenville 

 and Burgess. These specimens consist of alternating layers of cal- 

 careous spar, and a magnesian silicate (either serpentine, white py- 

 roxene, pyrallolite, or Loganite) — the latter minerals, instead of 

 replacing the skeleton of the organic form, really filling up the 

 interspaces of the calcareous fossil, as was discovered by Dr. Dawson, 

 to whose paper, and to that by Mr. Sterry Hunt, Sir William refers 

 for further details. ■ ' 



2. " On the Structure of certain Organic Remains found in the 

 Laurentian Rocks of Canada." By J. W. Dawson, LL.D., F.R.S., 

 F.G.S. With a Note by W. B. Carpenter, M.D., F.R.S., F.G.S. 



At the request of Sir Wm. Logan, Dr. Dawson carefully ex- 

 amined the laminated material thought by Sir William to have an 

 organic origin, and he found it to consist of the remains of an 

 organism which grew in large sessile patches, increasing at the 

 surface by the addition of successive layers of chambers separated 

 by calcareous laminae. Slices examined microscopically showed 

 large irregular chambers with numerous rounded extensions, and 

 bounded by walls of variable thickness, which are studded with 

 septal orifices irregularly disposed ; the thicker parts of the walls 

 revealed the existence of bundles of fine branching tubuli. Dr. 

 Dawson therefore concludes that this ancient organism, to which he 

 gave the name of Eozo'on Canadense, was a Foraminifer allied to 

 Carpenteria by its habits of growth, but of more complex structure, 

 as indicated by the complicated systems of tubuli ; it attained an 

 enormous size, and, by the aggregation of individuals, assumed the 

 aspect of a coral reef. • 



In a note, Dr. Carpenter corroborated Dr. Dawson's observations 

 on the structure and affinities of Eozo'on, but stated also that, as he 

 considered the characters furnished by the intimate structure of the 

 shell to be of primary importance, and the plan of growth to have a 

 very subordinate value, he did not hesitate to express his belief in 

 its affinities to Nummulina. 



3. " On the Mineralogy of certain Organic Remains found in the 

 Laurentian Rocks of Canada." By T. Sterry Hunt, Esq., M.A., 

 F.R.S., of the Geological Survey of Canada. 



Mr. Sterry Hunt first referred to the structure of Eozo'on as made 

 out by Dr. Dawson, and then stated that the mineral silicates oc- 

 curring not only in the chambers, cells, and canals left vacant by 

 the disappearance of the animal matter, but in many cases in the 

 tubuli, filling even their smallest ramifications, are a white pyroxene, 

 a pale-green serpentine and pyrallolite, and a dark-green alumino- 

 magnesian mineral which the author referred to Loganite. The 



