60 Canadian Record of Science. 
ing since they throw much fresh light on the charac- 
ter of the earliest known forms of these organisms, and 
their discovery is the more opportune from the fact that 
our knowledge of the existing hexactinellid sponges—the 
group to which all, or nearly all, these fossils belong— 
has been vastly increased by the work of Prof. F. H. 
Schulze, of Berlin, on the hexactinelled sponges dredged up 
by the Challenger expedition, and thus we are now better 
enabled than hitherto to compare the fossil and the recent 
forms. . 
Sir J. W. Dawson has already given a preliminary account 
of the character and stratigraphical relations of the rock 
in which the sponges occur, as well as some details of the 
fossils themselves, and at his invitation | now add some 
further comments thereto. 
In the present specimens, the amor dacsile or soluble silica 
of which their spicular skeletons were originally composed, 
has entirely disappeared, and the spicules now consist of 
iron pyrites. This replacement by pyrites is of common 
occurrence, more particularly in a matrix of black shales; 
for example, the earliest known sponge, Protospongia fenes- 
trata, Salter, from the Cambrian rocks of South Wales, is in 
the same mineral condition, and in a nearly similar matrix, 
as the specimens from the Quebec group and the Utica 
shale. When thus replaced, the general outline of the 
larger spicules is fairly distinct, but where the spicules 
are minute, and in close proximity to each other, their in- 
dividual outlines are blurred by the tendency of the crystals 
of the replacing pyrites to amalgamate together so as to 
form a coutinuous film of the mineral. in which the finer 
spicular structures are quite indistinguishable. This coales- 
cence of the pyrites likewise makes it very difficult to de- 
termine whether the spicular elements of the sponge were 
organically soldered together into a silicious mesh, or 
whether they were merely held in their natural positions 
by the soft animal structures, and owe their present union 
to subsequent fossilization. 
Next to the chemical changes, we have to take into 
