M. Otto Halm on Eozoon canadense. 271 



Under the microscope layer 1 presents a whitish transparent 

 amorphous matrix, and in this, traversing the stone in an 

 oblique direction so that but little of the matrix is to be seen, 

 hyaline crystals of dolomite, which, however, have their forms 

 not sharply developed. They have innumerable yellow en- 

 closures (picotite?). Sp. grav. 3*16, or that of dolomite. 

 The crystals lose themselves irregularly in 



Layer 2, the pure serpentinous mass. Under the microscope 

 traversed by bands with parallel striation, which (in polarized 

 light) immediately prove to be chrysotile. Sp. grav. 2*55. 

 This layer is sharply discriminated from 



Layer 3, the alternating layer. First a limestone band 5 rail- 

 lims. broad, then a serpentine band of equal breadth, and so 

 on. Limestone and serpentine bands, but constantly becoming 

 narrower, now alternate ; they are parallel, elongated, and cut . 

 off perpendicularly at the lateral ends. The limestone bands 

 effervesce with dilute hydrochloric acid and dissolve rapidly 

 and completahj. They therefore contain no silica. Sp. grav., 

 2*60. Distributed in the limestone, and more rarely in the ser- 

 pentinous mass, there are round and six-sided hyaline crystals. 

 These are arragonite. Here also are the canal- or branching- 

 systems. The latter, however, are not uniformly distributed 

 in the limestone, but only in particular granules (individuals). 

 I have found ten canal-systems to 7 cubic centims. The mass 

 of these systems is white by direct, and light brown by trans- 

 mitted light. In many places the origin of the canal-systems 

 from the spot where the arragonite crystals are maybe distinctly 

 recognized. They are never continued into the chambers, and, 

 indeed, have no relation at all to these. Nay, they even thicken 

 towards them in their stolons. Their form I take to be well- 

 known. 



What Carpenter calls the '' film," is a chrysotile layer around 

 the serpentine. This layer I have observed in nearly all 

 ophites. The aciculai are not tubes (even under the highest 

 magnifying-powers they contain no filling mass), but crystals. 



Layer 4. Now follows granular structure. The serpentinous 

 mass is in part not even yet quite homogeneous. We distinctly 

 see granides with olivine-polarization and cracks y even traces 

 of a lamination. The passages cease both towards the sides 

 and upwards. The arragonites are still present ; but instead 

 of the canal-systems there are only fissures round about 

 the arragonite granules, filled with the same milk-white mass 

 of which the canal-systems in No. 3 consist. 



IL Hand-specimen in the collection of the University of 

 Tubingen. 50 millims. long, 40 millims. broad. 



1-10 millims. sei-pcntine alternating with threads of chry- 



