302 Chronicles of Science. | April, 



The titles of the papers relating to the Laurentian Formation and 

 its Fossils are as follows : — 



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



Kocks of Canada." By Sir W. E. Logan. 



2. " On the Structure of certain Organic Eemains in the Lauren- 



tian Limestones of Canada." By Dr. J. W. Dawson. 



3. " On the Structure and Affinities of Eozoon Canadense." By 



Dr. W. B. Carpenter. 



4. " On the Mineralogy of certain Organic Eemains from the 



Laurentian Bocks of Canada." By Mr. T. Sterry Hunt. 



5. " On the Geological Structure of the Malvern Hills and 



adjacent Districts." By Dr. Harvey B. Holl. 



The discovery of the Eozoon has heen already recorded in this 

 Journal ; * a notice of the stratigraphical position and almost incon- 

 ceivable antiquity of the beds in which it was found was given at the 

 same time. Consequently, of the five papers, it will not be necessary 

 to refer more than incidentally to Sir William Logan's, and our space 

 will not allow us to enter very fully into the points discussed by Dr. 

 Holl and Mr. Sterry Hunt, as the chief interest is centred in the 

 descriptions of the structure, and the discussions on the affinities of 

 the fossil by Dr. Dawson and Dr. Carpenter. 



In place of the strictly technical descriptions of these distin- 

 guished observers, we give the following more popular digest of their 

 remarks on the structure of Eozoon, in understanding which the reader 

 will be assisted by the woodcuts on the next page. 



In general appearance (see Fig. 1), were it not for the materials 

 composing it, many specimens of Eozoon might be mistaken for gneiss, 

 as it consists of more or less contorted laminae, generally coarser in 

 one direction — probably towards the surface. In Fig. 1, the white 

 stripes represent the walls of the chambers, &c, and the dark ones the 

 chambers themselves filled with an infiltrated magnesian silicate. In 

 the diagram (Fig. 2), it will be seen that the walls (B, B) of the 

 chambers (A 1 , A 2 ) are perforated by a number of minute canals, which 

 give them under the microscope the appearance of a fringe of acicular 

 crystal, the canals being now filled with the same material as the 

 chambers. As the chambers grew old a thick calcareous shield, or 

 stony epidermis (C, C), called a " supplemental or intermediate 

 skeleton," was sometimes formed outside the " proper wall " (B, B, 

 just described) of the chambers. When this occurred, the next layer 

 of chambers (A 2 , A 2 ) was not in immediate contact with the previous 

 one, being separated from it by the " supplemental skeleton," but at 

 the same time connected with it by means of "stolons" (D), and a 

 canal-system (E). The individual chambers of the same layer either 

 open directly into one another (as at a, a), or communicate with one 

 another by passages through a shelly partition (as at b). There was 

 thus a free communication between the different chambers of the same 

 layer, and between certain chambers of different layers. 



* Vol. i. p. 475. 



