272 M. Otto Halm on Eozoon canadense. 



sotile ; 10-25 millims. serpentine as in I. ; 25-28 niillims. a 

 broad limestone band ; 29-40 millims. serpentine alternating 

 with limestone in nearly parallel bands, as in I. Seen from 

 the side, the bands lie in oblique lines ; the stone is therefore 

 probably composed of undulated layers. 



The limestone varies from hyaline to milk-white ; both 

 colours are seen in bands side by side. The cleavages are 

 distinctly visible. The arragonite forms small points. The 

 remaining 10 millims. are of granular structure. 



In polarized light the chrysotile at once catches the eye ; but 

 it is only necessary to make a rough section, and then the 

 white needles project from the matrix. Under the microscope 

 these chrysotile threads are seen almost everywhere on the 

 edges of the serpentine, but also in the limestone at its point 

 of contact with the serpentine, generally pei-pendicular to 

 both. 



III. Hand-specimen in the collection of the University of 

 Tubingen, presented thereto by Professor von Hochstetter. 

 100 millims. long, 60 millims. broad. Has a round serpentine 

 spot at one end. This circle is surrounded by alternate layers 

 of serpentine and limestone. At the opposite side there is 

 likewise a similar round spot. Between the two there is a 

 paler band (also limestone), bent so that the white appears like 

 a note of interrogation. At the end dolomite. Sp. grav. pro- 

 bably as in I. 3. 



In this specimen there are limestone fragments in the ser- 

 pentine passages. Several canal-systems may be seen even 

 with a power of 25 diameters ; in some it may be distinctly 

 perceived that they start from the disseminated arragonite. 



What is particularly remarkable in this specimen is that 

 the limestone forms layers with canal-systems only in small 

 surfaces ; by far the greater part is granular with distinct fluidal 

 structure, which can only be the consequence of a strong pres- 

 sure. In consequence of this the layers also are broken up 

 into spherical masses and mixed up together. In many 

 places there are black points in the limestone ; these are 

 very probably graphite. 



What follows applies to all the three specimens : — 



The serpentine undoubtedly originated from olivine which 

 got into a mass of limestone while the latter was still soft. 

 When the decomposition took place quietly and no pressure 

 intervened, the serpentine would at first retain the form of 

 the olivine, but by further decomposition the soft granule 

 would first of all become squeezed flatter in consequence of 

 the pressure exerted by the overlying mass. If no way of 

 escape presented itself, or if an opposing pressure occurred 



