74 PRINCIPLES OF PALHONTOLOGY. 
filled to its minutest internal recesses with the substance of the 
living animal, and covered externally with a layer of the same 
substance, giving off a network of interlacing filaments. 
Such, in brief, is the structure of the living /oraminifera ; 
and it is believed that in Hozodz we have an extinct example 
of the same group, not only of special interest from its imme- 
morial antiquity, but hardly less striking from its gigantic 
dimensions. In its original condition, the entire chamber- 
system of “ozodn is believed to have been filled with soft 
structureless living matter, which passed from chamber to 
chamber through the wide apertures connecting these cavities, 
and from tier to tier by means of the tubuli in the shell-wall and 
the branching canals in the intermediate skeleton. Through 
the perforated shell-wall covering the outer surface the soft 
body-substance flowed out, forming a gelatinous investment, 
from every point of which radiated an interlacing net of deli- 
cate filaments, providing nourishment for the entire colony. 
In its present state, as before said, all the cavities originally 
occupied by the body-substance have been filled with some 
mineral substance, generally with one of the silicates of mag- 
nesia; and it has been asserted that this fact militates strongly 
against the organic nature of Lozodn, if not absolutely dis- 
proving it. As a matter of fact, however—as previously no- 
ticed—it is by no means very uncommon at the present day 
to find the shells of living species of Foraminifera in which 
all the cavities primitively occupied by the body-substance, 
down to the minutest pores and canals, have been similarly 
injected by some analogous silicate, such as glauconite. 
Those, then, whose opinions on such a subject deservedly 
carry the greatest weight, are decisively of opinion that we are 
presented in the Zozoon of the Laurentian Rocks of Canada 
with an ancient, colossal, and in some respects abnormal type 
of the Foraminifera. In the words of Dr Carpenter, it is not 
pretended that “‘the doctrine of the Foraminiferal nature of 
Lozoon can be proved in the demonstrative sense;” but it 
may be affirmed “that the convergence of a number of separate 
and independent probabilities, all accordant with that hypothesis, 
while a separate explanation must be invented for each of 
them on any other hypothesis, gives it that Aigh probability 
on which we rest in the ordinary affairs of life, in the verdicts 
of juries, and in the interpretation of geological phenomena 
generally.” 
It only remains to be added, that whilst Hozodn is by far 
the most important organic body hitherto found in the Lauren- 
tian, and has been here treated at proportionate length, other 
