On Specimens of Eozoon Canadense. 211 
1. In some specimens the serpentine filling the chambers 
presents a laminated appearance, as if deposited in successive 
layers. There even occur serpentine-lined cavities and ca— 
nals with calcareous filling. This may depend on the depo- 
sition of serpentine in coatings on the sides of those cavities, 
leaving perhaps a central portion to be filled with calcite, 
or may in some cases be the result of the filling of the cavi- 
ties with successive laminz of serpentine from below upward. 
In either case we have frequent examples of these varieties 
of filling in ordinary fossils. 
2. There are examples of Hozoon in which no serpentine 
or other mineral filling appears, and in which the whole 
mass is calcareous, though presenting canals filled with ser- 
pentine or dolomite. In these cases the explanation is that 
the mass of Eozoon has not had its cavities filled, but has 
been compressed by pressure into asolidmass. Such astate 
of preservation is often observed in other fossils, more es- 
pecially in fossil wood, in which the cell-walls often become 
under pressure wholly coalescent. 
3. The condition of the proper wall also illustrates the 
manner of preservation. The tubes which compose it areso 
extremely fine that they are rarely injected with silicates, 
Sometimes they are merely occupied with calcite, and in 
this case the wall constitutes an apparently structureless 
band, or merely presents a band of slightly different appear- 
ance from the remainder. Sometimes the tubuli appear as 
fine continuations of the canals; or as a more or less perfect 
fringe of fine lines, and in decalcified specimens, this part is 
often represented merely by a tabular space between the ends 
of the canals and the serpentine filling. In the best specimens 
and in very thin slices under a high power, these tubuli ap- 
pear as hollow threads with expanded terminations, but this 
is rarely to be seen, All these conditions may be equally 
well observed in Nummulites injected with glauconite. 
4. The larger masses of Hozoon have often suffered con- 
siderable contortion and even faulting, and this seems to 
have occurred in some instances previous to complete fossil- 
ization. ‘This is a condition often observed in fossils of all 
