INTRODUCTION. XVli 



the mineralogy of "Eozoon Canadense." He has brought under 

 notice a specimen of the presumed fossil from the Calumet, 

 which " exhibits the whole of the sarcode replaced by serpen- 

 tine ; while, in another one from the same locality, a layer of 

 pale green translucent serpentine occurs in immediate contact 

 with white pyroxene." 



There is very little difference, then, between the latter speci- 

 men and the one we have had under notice. Yes, we beg 

 pardon, there is a difference : in Sterry Hunt's specimen there 

 are " very thin " calcareous layers (" septa ") which run 

 " transverse to the plane of contact of the two minerals"; yet 

 they are seen to traverse both the pyroxene and the serpentine 

 without any interruption or change/' It is to be apprehended 

 that Dr. Hunt, in bringing forward this specimen with its calca- 

 reous septa intersecting the serpentine layers, lays himself open 

 to the doubt of his being sufficiently acquainted with the struc- 

 ture of "Eozoon Canadense " as diagnosed by his colleagues. 



No view which contends for the inorganic origin of the 

 different eozoonal features can be considered satisfactory 

 unless it be consistent with facts pertaining to mineralogy, 

 geology, or chemistry. With respect to the "chamber-casts" 

 and the " proper wall," their origin, as products answering to 

 these terms, will be made clear in the following pages ; but as 

 regards the "canal system," a point in connexion therewith 

 requires some consideration ; for we freely admit that this part 

 possesses peculiarities which seemingly do not strictly accord 

 with ordinary mineral developments, except, it may be, in the 

 case of certain dendritic bodies characteristic of " moss agates." 

 But although at the commencement of our examination of 

 "Eozoon " we felt inclined to identify the " canal system" with 

 the latter products, it was never quite clear to us that we were 

 in the line of the correct view, especially when there were palpable 

 evidences at hand showing that the variety which generally 

 presents itself in the Canadian " eozoonal " ophite had originated 

 through a wasting or decretory process of its compone&t sub- 



b 



