THE LAURENTIAN KOCKS. 23 



nodules of pyroxene and serpentine, and it contains 

 subordinate beds of dolomite. In one layer only, and 

 this but a few feet tbick, does tbe Eozoon occur in any 

 abundance in a perfect state, though fragments and 

 imperfectly preserved specimens abound in other parts 

 of the bed. It is a great mistake to suppose that it 

 constitutes whole beds of rock in an uninterrupted 

 mass. Its true mode of occurrence is best seen on the 

 weathered surfaces of the rock, where the serpentinous 

 specimens project in irregular patches of various sizes, 

 sometimes twisted by the contortion of the beds, but 

 often too small to suffer in this way. On such 

 surfaces the projecting patches of the fossil exhibit 

 laminas of serpentine so precisely like the Stromatoporce 

 of the Silurian rocks, that any collector would pounce 

 upon them at once as fossils. In some places these 

 small weathered specimens can be easily chipped off 

 from the crumbling surface of the limestone ; and it is 

 perhaps to be regretted that they have not been more 

 extensively shown to palaeontologists, with the cut 

 slices which to many of them are so problematical. 

 One of the original specimens, brought from the 

 Calumet, and now in the Museum of the Geological 

 Survey of Canada, was of this kind, and much finer 

 specimens from Cote St. Pierre are now in that col- 

 lection and in my own. A very fine example is repre- 

 sented, on a reduced scale, in Plate III., which is taken 

 from an original photograph.* In some of the layers 

 are found other and more minute fossils than Eozoon, 

 * By Mr. Weston, of the Geological Survey of Canada. 



