20 
in the progress of this science, and until it is known by what agent the 
earth of flints has, at some former period, existed so generally and so 
plenteously in solution. 
The specimen of marble, Plate III. Fig. 3, from Wales, evidently owes 
its configurations to this tubipore. In several parts may be seen different 
sections of the tubes, filled by white spathose matter. In some parts of 
marble, sections of the connecting branches may also be perceived ; by ‘ 
which it appears, that they exactly agree, in their mode of ramification, 
and in the direction which they preserve, with that which is observable 
in the specimen, Plate III. Fig. 1. 
The next species of the genus tubipore which claims our notice, is 
the CHAIN CORAL, (tuhipora catenulata, Linn.) composed of parallel 
tubes, formed in laminae anastomosing by their winding folds. 
This curious zoophyte has been only found in a fossil state. The 
flattened oval tubes, of which it is composed, being placed perpendi- 
cularly in a waving line ; finely grooved, thin, upright folds, are formed 
by the sides of the tubes, whilst their upper, and oftentimes their 
lower, surfaces, present an appearance exceedingly resembling that 
of a small chain. Its appearance is frequently so beautiful as to 
resemble figures, formed by the tool of the most delicate workman, or 
by the needle of the embroiderer : and the folds, by frequently coming 
into contact with each other, make it appear as if the chain was so 
connected as to form a net. This curious reticular form, as is observed 
by Bromell, does not yield a bad representation of a retiform plexus 
of lymphatic vessels.* 
The folds of this coral are of various heights : the\ , oftentimes, are 
not more than a quarter of an inch in height; and seldom exceed 
six inches. The interstices between the folds of the coral, as well 
as the tubes themselves, are generally filled up with a mixture of 
argillaceous and calcareous earth. A considerable difference, how- 
ever, is found in the matrix in which different specimens of this fossil 
* Bromellii Lithograph. Vide Spec. 2, 25. Tab. 25. 
