1866.] KING AND ROWNEY — ^' EOZOONAL EOCK." 201 



specimens which he digested, are, in our opinion, homologous to the 

 "definite shapes"*. Pieces of impure "primary" marble from 

 Barna-Oran, Connemara, treated in the same way, have yielded to 

 us numerous aggregations of crystals apparently belonging to actino- 

 lite. Another marble of the like kind, from a neighbouring locality, 

 contains irregular lumps, having a lamello -prismatic structure, which 

 appear to be diopside. A very impure " primary " limestone, from 

 Donegal, containing large crystals of a brown mineral, apparently 

 Epidote, is filled with prismatic masses, the prisms being either 

 parallel or radiating. These examples have certainly no resemblance 

 to the " definite shapes ; " but it will shortly be seen that there is a 

 relationship between the former and certain representatives of the 

 latter occurring in different varieties of " eozoonal " Ophite. 



The so-called " Moss-agates " often contain beautiful arborescent 

 and foliated forms. The specimen already noticed contains a number 

 of thickish vermicular shapes, seemingly composed of hydrous per- 

 oxide of iron : their branchings and anastonicfeings, amidst a mass 

 of transparent chalcedony, forcibly remind one of some of the simplest 

 of the " definite shapes." We have also in our possession a beautiful 

 specimen, obtained along with a large number collected at Oberstein, 

 which is crowded with slender cylindrical dendritic ramifications, 

 red, green, and yellow, evidently all hydrous oxides of iron : several 

 of these so decidedly resemble the more complex structures in ques- 

 tion as to surprise us that no one has suggested the possibility of 

 their identity of origin. For our part, we unhesitatingly accept 

 this last case as proving that the so-called " canal- system " of 

 " Eozoon Canadense " is a phenomenon of " imitative crystallization." 



Perhaps none of the imbedded crystallizations we have brought 

 forward agree chemically with the " definite shapes." Those which 

 are most nearly allied to them in this respect do not present their 

 identical form. There is a case, however, as yet unnoticed, against 

 which such an objection cannot be urged — ^namely, metaxite from 

 Beichenstein. This mineral, which occurs imbedded in saccharoidal 

 calcite, crystallizes in ramose and dendritic forms of a pale-green or 

 whitish colour, opaque or somewhat porcellanous, and compact 

 or fibre -foliaceous in texture. The crystallizations occur both erect 

 and spreading : our largest specimen is about an inch in diameter ; 

 but they are found much less. One of our smallest, obtained by de- 

 calcification, is represented in PI. XY. fig. 12, magnified 110 diameters. 

 It is undistinguishable from some of the palmated dendritic " definite 

 shapes " characteristic of GrenviUe and Connemara Ophite ; and, ac- 

 cording to Delesse's analysis, it is doubtless chemically identical with 

 themf. We have therefore no hesitation in concluding that the so- 

 called " representatives of the canal-system " of ^^ Eozoon Canadense " 

 are no other than crystallizations of metaxite, an allomorphic variety 

 of serpentine. 



Eeverting to the "amorphous masses," Dr. Carpenter, while 

 investigating the structure of" eozoonal " Ophite, undoubtedly passed 



* See ' Philosophical Magazine,' 4th ser. vol. xvii. pp. 169-176. 

 t See analysis of metaxite in a preceding page. 

 Vol. XXII. PART I. Q 



