M. Otto Halm on Eozoon caiiadense. 279 



Witli this I might conclude my work. But as I do not 

 wish to fall short even in the smallest degree with respect to 

 the evidence in contradiction and its foundation, I pass on to 



2. The Mineraloqical Facts. 



In the formation of the Canadian ^o;2!oo?i-serpentines only 

 three minerals seem at the first glance to take part — dolomite, 

 serpentine, and limestone. 



On closer investigation, however, other minerals occurred : — 



No. II. has superiorly a clirysotile hand, 7 millims. in breadth, 

 which is frequently repeated in the serpentine. Whenever I 

 ground the surface of the plate rather rough, a thread of silvery 

 lustre appeared everywhere around the serpentine bands ; and 

 this was not merely asbestos-like, but actually asbestos, namely 

 chrysotile. 



Besides chrysotile, arragonite occurs in disseminated clear 

 grains, and even in six-sided prisms. 



The arragonite is surrounded by the same mass that forms' 

 the canal-systems ; this is white by direct, brown by transmitted 

 light. When treated with acid, it dissolves at the same time 

 with the limestone. If the canal-systems were connected with 

 the chambers and, as Carpenter thinks, injected with serpen- 

 tine-mass from the latter, they ivould not dissolve at all in acid ; 

 they must be serpentine and show the colour and polarization 

 of serpentine. Where there are serpentine grains, the same 

 white mass passes into the fissures surrounding the serpentine 

 grain. It is only in the alternating layers that the canal- 

 systems are in the limestone ; and frequently their origin on the 

 disseminated arragonite grains may be distinctly detected. 



Hence we get the following as to the formation of the 

 stone : — 



The serpentine grains were originally olivine. During 

 their decomposition they swelled up, and in consequence burst 

 up the surrounding limestone, when the fluid white calcareous 

 mass entered into the fissure. But where the limestone mass 

 was still soft when the serpentine mass swelled up in it, either 

 the extending serpentine mass itself pressed the white calca- 

 reous fluid into the limestone, when the canal-systems were 

 formed, or a pressure was produced upon the whole mass, and 

 then the same effect occurred, only the immediate cause was 

 different. 



It was undoubtedly either a pressure from within, caused by 

 the decomposing olivine grains, or one from without upon the 

 whole mass, that produced the canal-systems. This is proved 

 even by their form. In the first place, they are quite irregular 



