090 «Sir Wm. Dawson—New Facts as to Eozobn Canadense. 
become confounded in a general vesicular or acervuline layer. I 
feel now convinced that broken fragments of this upper surface 
scattered over the sea-bottom formed those layers of Archeospherine 
which at one time I regarded as distinct organisms. 
It is to be observed, however, that other forms of Eozoon occur. 
More especially there are rounded or dome-shaped masses, that seem 
to have grown on ridges or protuberances, now usually represented 
by nuclei of pyroxene. 
2. Pores or Oscula. 
In the large number of specimens of Eozoon which have been cut or 
sliced in various directions, and are now in our Museum at Montreal, 
it has become apparent that there are more or less cylindrical 
depressions or tubes, sometimes filled with serpentine and some- 
times with inorganic calcite, crossing the lamine at right angles. 
These seem to occur chiefly in the large and confluent masses, and 
are without any regular or definite arrangement. In some of the 
narrower openings of this kind the lamine can be observed to sub- 
divide and become confluent on the sides of these tubes, in the same 
manner as at the external surface. This circumstance induces me 
to believe that these are not accidental, but original parts of the 
structure, and intended to admit water into the lower parts of the 
masses. A characteristic example of a fortunately weathered 
specimen is seen in the photograph accompanying this paper. (See 
Pl. IV. Fig. 2.) A central canal of a similar kind is well shown in 
the accompanying illustration. 
Section of the base of a turbinate or top-shaped Hozoom. This specimen shows 
an osculiform, cylindrical perforation, cut in such a manner as to show its reticulated 
wall and the descent of the lamine toward it. Two-thirds of natural size. Coll. 
Carpenter. 
[This illustration (from Prof. Prestwich’s ‘‘Geology,’’ vol. ii. p. 21) has been 
courteously lent by the Clarendon Press, Oxford. ] 
