King and Rowney — On Eozoon Canadense.'' 
149 
are more or less paralleled by the grains of the mineral silicates in the 
pre-cited marbles. 
4th. The ''chamber casts" being composed occasionally of loganite 
and malacolite, besides serpentine, is a fact which, instead of favouring 
their organic origin, as supposed, must be held as a proof of their 
having been produced by mineral agencies ; inasmuch as these three 
silicates have a close pseudomorphic relationship, and may, therefore 
replace one another in their naturally prescribed order. 
5th. Dr. Giimbel, observing rounded, cylindrical, or tuberculated 
grains of coccolite and pargasite in crystalline calcareous marbles, 
considered them to be ''chamber casts," or of organic origin. "We have 
shown that such grains often present crystalline planes, angles, and 
edges ; a fact clearly proving that they were originally simple or 
compound crystals that have undergone external decretion by chemical 
or solvent action. 
6th. "We have adduced evidences to show that the *' nummuline 
layer" in its typical condition — that is, consisting of cylindrical aciculi, 
separated by interspaces filled with calcite — has originated directly 
from closely packed fibres these from chrysotile or asbestiform ser- 
pentine ; this from incipiently fibrous serpentine ; and the latter from 
the same mineral in its amorphous or structureless condition. 
7th. The "nummuline layer," in its typical condition, unmistakably 
occurs in cracks or fissures, both in Canadian and Connemara ophite. | 
8th. The " nammuline layer is paralleled by the fibrous coat which 
is occasionally present on the surface of grains of chondrodite.]: 
9th. We have shown that the relative position of two superposed 
asbestiform layers (an upper and an under " proper wall"), and the 
admitted fact of their component aciculi often passing continuously and 
without interruption from one " chamber cast" to another, to the 
exclusion of the " intermediate skeleton," are total y incompatible with 
the idea of the "nummuline layer" having resulted from pseudopodial 
tubulation.§ 
10th. The so-called " stolons," and " passages of communication 
exactly corresponding with those described in Cycloclypeus,'''' have been 
shown to be tabular crystals and variously formed bodies, belonging to 
* All that we have observed in connexion with the structural changes of ser- 
pentine in "eozoonal rocks," and the relations of this mineral to the adjacent calcite 
— whether occupying the narrow spaces between the aciculi of the "nummuline 
layer," or the wider ones between the " chamber casts," — has led us to the belief 
that the latter mineral is a replacement pseudomorph after the former. Our inter- 
pretation of the facts, which have given rise to this view, has not been shown to be 
wrong in any respect. 
t " Quarterly Journal Geological Society, vol. xxii., pi. xiv., fig. 4, p. 196 ; 
"Proc. Royal Irish Academy," vol. x., pi. xlii., fig. 5, 6. 
X "Quarterly Journal Geological Society," vol. xxii., pi. xiv., figs. 5, 6, pp. 
196, 197. 
§ 7(5., vol. xxii., p. 191 ; " Proc. Royal Irish Academy," vol. x., p. 517. 
