354. = Mr. H. J. Carter on the assumed Relationship 
other hand, consists of the open mouths of the tubes in juxta- 
position, as seen on the surface of the fossil, the whole of the 
structure of Parkeria is elaborated out of tissue composed of 
anastomosing, reticulated and vermiculated, solid, calcareous 
thread in which there is no epithecal or other differentiation 
whatever beyond form ; that is to say, that although this tissue 
is traversed by distinct tubes which radiate in broken lines 
from the centre to the circumference (passing through the 
chambers in an isolated manner, that is, separated for some 
distance from each other without any intervening substance, 
which chambers, as before stated, are empty in the fossil 
Polyzoa from the Coralline Crag), the tubes themselves of 
Parkeria are composed of the same reticulated tissue as the 
rest of the fossil. In both instances, of course, these calca- 
reous structures respectively represent the skeletal or hard 
parts, while the intervals were occupied by the soft parts of 
the animal. 
Again, the embryo or commencement of Parkeria seems to 
have settled, for development, on a loose or rolling fragment 
of foreign material, whence the future growth became more 
or less spherical, often including in its progress small Fora- 
minifera and other particles of foreign matter, as may be seen 
by the vertical sections. 
Thus the resemblance of the fossilized Polyzoa of the Crag 
to Parkeria is reduced to the general structure, while the ele- 
mentary structure is totally different. 
Where Parkeria looks most like the fossilized forms of the 
Polyzoa from the Crag is in the solidified specimens, that is, 
where the cavities originally occupied by the flesh or soft 
parts have been filled up with calcite; but this is not the 
condition in which the comparison should be made, seeing 
that, in many instances when the Parkeria is broken with a 
hammer, more or less of the interior comes out in a large 
spherical form or nucleus, like a nut from its shell, wherein 
the whole of the calcite, which in the solidified specimens fills 
the intervals originally occupied by the soft parts, is absent, 
and therefore nothing but the tissue formed of the anastomo- 
sing, reticulated, skeletal thread, now incrusted with minute 
crystals of calcite through fossilization, remains, which nucleus, 
on being picked to pieces as much as may be required, can 
be most satisfactorily studied, and then it is that the great 
difference which exists between it and the fossilized Polyzoa 
of the Coralline Crag can be fully realized. Indeed, in this 
condition, the skeletal part can be more satisfactorily studied 
even than in the living animal, when the whole of the skeleton 
was probably imbedded in flesh. 
