130 THE NATTTRAL HISTOKY EETIEW. 



represent the Upper Greensand, the Chalk-marl, and the lower part 

 of the Lower Chalk of England, and to be the miniature counterpart 

 of D'Orbigny's Etage Cenomanien. It nowhere exceeds 55 feet in 

 thickness ; but it nevertheless contains the following beds: — (1) 

 Chloritic sands and sandstones of Colin Glen, or the Zone of Exogyra 

 columha; (2) Chloritic sandstones of Woodburn, or the Zone of 

 Inoceramus Crispi; (3) Yellow-sandstones and Marls with Chert, 

 or the Zone of Ostrea carinata; and (4) Glauconitic sands, or the 

 Zone of Exogyra conica. The authors concluded by giving descrip- 

 tions of several new species of fossils, chiefly from the " White 

 Limestone" and the Sponge-bearing zone. 



3. " On the Eecent Earthquake at St. Helena." By Governor 

 Sir C. Elliot, K.C.B. Communicated by the Colonial Secretary 

 through Sir C. Lyell, Bart., E.E.S., E.G.S. This earthquake, which 

 is stated to be the fourth that has occurred during the two centuries 

 that we have been in the occupation of the island, occurred at about 

 4h. 10m. A.M. on July 15th, and in this paper Sir C. Elliot described 

 the nature of the shock and the circumstances attending it. 

 November 2Srd, 1864. 

 The following communications were read : — 

 1. " On the occurrence of Organic Eemains in the Laurentian 

 Eocks of Canada." By Sir W. E. Logan, LLD., E.E.S., E.G.S., 

 Director of the Geological Survey of Canada. The oldest known 

 rocks of North America, composing the Laurentide Mountains in 

 Canada, and the Adirondacks in the State of New York, have been 

 divided by the Geological Survey of Canada into two unconformable 

 groups, which have been called the Upper and Lower Laurentian 

 respectively. In both divisions zones of limestones are known to 

 occur, and of them at least three have been ascertained to belong to 

 the Lower Laurentian. Erom one of these limestone-bands, occurring 

 at the Grand Calumet on the Eiver 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 calcareous spar, and a magnesian 

 silicate (either serpentine, white pyroxene, 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 Eemains found in the 



