18 ROCK-METAMOKPH1SM. 



as showing how the aciculse forming the " nummuline wall" of 

 "Eozoon Canadense" have originated, we admit, from its posi- 

 tion, and from apparently being no more than a mere crack 

 across a " chamber cast/' that it cannot be recognized as contain- 

 ing genuine examples of aciculse belonging to this ' ' wall/' It is 

 therefore some feeling of satisfaction to us to find that we are 

 enabled to bring forward a case against which no objections of 

 this kind can be urged. 



A number of specimens, some of which have been added to 

 the geological museum of Queen's College, Galway, were lately 

 received by Mr. Damon, F.G.S., of Weymouth, from Principal 

 Dawson, as indisputable examples of "Eozoon Canadense," col- 

 lected in the type locality, Ottawa. 



Pig. 2, Plate IX., represents a portion of one of the specimens. 

 It consists of interlamellations of serpentine and calcite in mutual 

 parallelism, the former being often converted entirely, or partly 

 into chrysotile. In many instances a layer of serpentine con- 

 sists of separated but contiguous laminae of chrysotile parallel 

 amongst themselves. This parallelism of arrangement between 

 the calcite,, serpentine, and chrysotile is the general rule in the 

 present specimens, as it is in others we have at different times 

 brought under notice. 



Of the two layers, coloured green in the figure, the undermost 

 one consists the lower half of colloidal or amorphous serpentine, 

 and the upper half of typical chrysotile : the uppermost layer 

 is composed of what at first sight might be taken for ordinary 

 serpentine, but which, on close examination with powers of 25 

 and 40 diameters, turns out to be in the state of incipient 

 chrysotile, being traversed by separated fine filiform cuts, 

 which seem to give rise to a columnar structure. The direction 

 (which slightly deviates from the perpendicular) of the cuts and 

 the columns, it is noteworthy, is the same as that taken by the 

 fibres Of the underlying chrysotile. 



On the left half of the upper surface of the layer containing 

 typical chrysotile may be clearly seen the fibres passing con- 

 tinuously into a series of definite but closely adhering acicula?, 

 and on the right half into similar acicula3 : here, however, they 

 are distinctly separated by interspaces filled in with calcite. 

 In eozoonal parlance the latter aciculse are " casts of tubuli " 

 in undisturbed relation to the " intermediate skeleton " and its 



