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 the 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, (tubipom catenulata, Linn.) composed of parallel 

 tubes, formed in laminae anastomozing 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 coining 

 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 : they, 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- 



c? 



ever, is found in the matrix in which different specimens of this fossil 

 * Bromellii Lithograph. Vide Spec. 2, 25. Tab. 25. 



