18G8.] MISCELLANEOUS. 321 



mineralogically homogeneous, and only structurally distinguishable, 

 by the effect of their junction-surfaces on the course of faint rays 

 of light transmitted through them.— W. B. C] 



Explanation of the Plates. 



Plate II. 

 Specimen of Eozoon Canadense, imbedded in a dark-coloured homo- 

 geneous limestone, occurring in the Lower Laurentian series 

 in Tudor, Ontario ; two-thirds of the natural size. 



Plate III. 



Fig. 1. Section of one of the calcareous layers of the Tudor specimen 

 (Plate IL), showing canal-system imperfectly infiltrated with 

 black (carbonaceous '?) matter; magnified 120 diameters. 



2. Section of the shelly layer of a specimen of Eozoon from Gren- 



ville, showing a minute form of canal-system, partly injected 

 with black matter and partly with serpentine ; magnified 120 

 diameters. 



3. Siliceous bodies (internal casts?) from a specimen of Eozoon 



from 'Wentworth ; magnified 50 diameters. 



4. 5. Sections of a fragment of Eozoon from the Hadoc limestone, 



showing various forms of canal-system filled with carbonate 

 of lime ; magnified 120 diameters. 



MISCELLANEOUS 



XOTE OX SUPPOSED BURROWS OF WORMS IX THE 

 LAUREXTIAX ROCKS OF CAXADA. 



By J. W. Dawsox, LL.D., F.R.S., &c. 



Among other indications of fossils in the Laurentian rocks, men- 

 tioned in my paper on the structure of Eozoon, are certain per- 

 forations resembling burrows of worms, found in a calcareous 

 quartzite or impure limestone from Madoc, in Upper Canada. 

 They occur in specimens in the Museum of the Geological Survey, 

 and also in specimens subsequently collected by myself at the same 

 place. 



The beds at Madoc, containing these impressions, underlie, un- 

 conformable, the Lower Silurian limestones, and are regarded by 

 Sir W. E. Logan as belonging to a somewhat higher horizon in the 

 Laurentian, than the Eozoon Serpentines of Grenville. They are 

 also less highly metamorphosed than the Laurentian rocks gener- 



VoL III. U Xo. 4. 



