312 THE CANADIAN NATURALIST. [Jan. 



ON EOZOON CANADENSE .* 



By J. W. Dawson, LL.D., F.R.S., F.G.S. With Kotes by "W. B. 

 Carpenter, M.D., F.R.S. 



I. SPECIMEN OF EOZOON FROM TUDOR, ONTARIO. 



This very interesting specimen, submitted to me for examination 

 by Sir. W. E. Logan, is, in my opinion, of great importance, as 

 furnishing a conclusive answer to all those objections to the organic 

 nature of Eozoon which have been founded on comparisons of its 

 structures with the forms of fibrous, dendritic, or concretionary 

 minerals, — objections which, however plausible in the case of 

 highly crystalline rocks, in which organic remains may be simulated 

 by merely mineral appearances readily confounded with them, are 

 wholly inapplicable to the present specimen. 



1. General appearance. — The fossil is of a clavate form, six 

 and a half inches in length, and about four inches broad. It is 

 contained in a slab of dark-colored, coarse, laminated limestone, 

 holding sand, scales of mica, and minute grains and fibres of 

 carbonaceous matter. The surface of the slab shows a weathered 

 section of the fossil (PI. II.) ; and the thickness remaining in the 

 matrix is scarcely two lines, at least in the part exposed. The 

 septa, or plates of the fossil, are in the state of white carbonate of 

 lime, which shows their form and arrangement very distinctly, in 

 contrast to the dark stone filling the chambers. The specimen lies 

 flat in the plane of stratification, and has probably suffered some 

 compression. Its septa are convex towards the broad end, and 

 somewhat undulating. In some places they are continuous half- 

 way across the specimen ; in other places they divide and re-unite 

 at short distances. A few transverse plates, or connecting columns, 

 are visible ; and there are also a number of small veins or cracks 

 passing nearly at right angles to the septa, and filled with 

 carbonate of lime, similar in general appearance to the septa 

 themselves. 



On one side, the outline of the fossil is well preserved. The 

 narrow end, which I regard as the basal portion, is rounded. The 

 outline of the side first bends inward, and then outward, forming 

 a graceful double curve, which extends along the greater part of 

 the length. Above this is an abrupt projection, and then a sudden 



* From the Quar. Jour. Geol. Soc, Aug. 1867. Read before the 

 Geological Society, May 8, 1867. 



