160 THE CANADIAN NATURALIST. 



organic form externally resembling Stromatoceriian, and found in 

 the Laurentian limestone of the Ottawa. These were described by 

 me in the Canadian Naturalist for that year (vol. iv, p. 300), 

 and afterwards figured in the Geology of Canada, p. 49. In 

 1863, similar forms were detected by the Geological Survey, in 

 the serpentine-limestone of Grenville, sections of which we have 

 prepared and submitted for microscopic examination to Dr. J. W. 

 Dawson. He finds that the serpentine, which was supposed to 

 replace the organic form, really fills the interspaces of the calcareous 

 fossil. ' This exhibits in some parts a well-preserved organic 

 structure, which Dr. Dawson describes as that of a Foraminifer 

 ' growing in large sessile patches after the manner of Carpenter ia, 

 but of much greater dimensions, and presenting minute points 

 which reveal a structure resembling that of other foraminiferous 

 forms, as for example Calcarina and NitmmiditesJ Figures and 

 descriptions will soon be published by the Geological Survey. 



" Large portions of the Laurentian limestones appear to be made 

 up of fragments of these organisms, mixed with other fragments 

 which suggest comparisons with crinoids and other calcareous fos- 

 sils, but cannot be distinctly determined. Some of the limestones 

 are more or less colored by carbonaceous matter, which Dr. Dawson 

 has found to exhibit under the microscope evidences of organic 

 structure, probably vegetable. 



" In this connection, it may be noticed that Mr. Sterry Hunt, in 

 a paper presented to the Geological Society of London in 1858, (see 

 also Silliman's Journal, [2], xxxvi, 296,) insisted upon the presence 

 of beds of iron-ore, metallic sulphurets, and graphite in the Lau- 

 rentian series as " aff"ording evidence of the existence of organic 

 life at the time of the deposition of these old crystalline rocks." 



Dr. Dawson has proposed for this fossil the name of Eozoon 

 Canadense, under which it will shortly be fully described. 



Published, Montreal, May 7, 1861. 



