1866.] GUMBEL — ON LAURENTIAN ROCKS. 99 



are consequently of organic origin. From the great similarity 

 between the forms of the pargasite grains and the Eozoon- 

 serpentine, we may fairly be permitted to assume the presence of 

 Eozoon in the crystalline limestones of Finland.* 



Similar relations are doubtless to be met with throughout the 

 crystalline limestones of Scandinavia, wherever such mineral 

 species occur in rounded grains or in tuberculated forms. The 

 notion that these forms are of organic origin, and have been 

 moulded in the spaces left in a calcareous skeleton by the decay of 

 animal matter, receives a strong support from the observations of 

 Nordenskiold and Bischof. The former found in a tuberculated 

 pyrallolite, 6-38 per cent, of bituminous matter, besides 3-58 per 

 cent, of water ; while Bischof states that the same mineral 

 becomes black when ignited, and when calcined in a glass tube, 

 gives off a clear water with a very offensive empyreumatic odor. 



There may also be mentioned in this connection a phenomenon 

 which is probably related to those just described. Upon the 

 pyritous layers which occur in the Hercynian gneiss near Boden, 

 are found great quantities of grains of quartz, almost transparent, 

 and with a fatty lustre, which have in all cases rounded undulating 

 forms, precisely resembling the pargasite tubercles from Finland. 

 Dichroite also sometimes occurs in this region in similar shapes, 

 although it also, in many cases, forms perfect crystals. The 

 evidence of organic forms may perhaps be found in these masses of 

 quartz and dichroite, though their treatment will necessarily 

 present difficulties. 



A specimen of crystalline limestone, with rounded pyroxene 

 (coccolite) grains from New York, showed, after etching by 

 means of acids, no traces of tubuli ; but the grains of coccolite, 

 remaining after the entire removal of the carbonate of lime, 

 were found to be connected with each other by numerous fine 

 cylindrical tubuli and skin-like laminae. The surface of the 

 rounded coccolite grains was much wrinkled, and studded with 

 small cylindrical processes of a white mineral, sometimes ramifying, 

 and apparently representing the remnants of a system of tubuli 

 which had been destroyed by the crystallization of the carbonate 

 of lime. The flaky residue from the solvent action of the acid 

 exhibits, under the microscope, laminae, needles, and strings of 



* These belong to the primitive gneiss formation of Scandinavia, 

 which the geologists of Canada, so long ago as 1855, referred to the 

 Laurentian system. — T. S. H. 



