29 



That the formation of these turbinated madrepores may have been 

 thus effected does not appear difficult to conceive. Neither is it 

 difficult to understand, that when the animal had attained its full 

 extent of growth, the continuance of its labours would produce, not 

 a body of a conical, but of a cylindrical form. Nor does it appear 

 unlikely that should any accidental circumstance change its horizontal 

 position, a proportional deflection from the straight line would be 

 occasioned ; and a coralline body of a curved form be produced. Spe- 

 cimens of both these forms, it has been just remarked, are frequently 

 found. 



The appearances yielded by two sections of this species of madre- 

 porite are represented, Plate IV. Fig. 13, 14. Fig. 14, is a section 

 made at about an inch from the pedicle, and Fig. 13, is a section 

 made after the madrepore had assumed a cylindrical form. In the former 

 of these it will be observed, that both the converging and the con- 

 centric laminae are much fewer than in the latter. In consequence of 

 this, a considerable degree of dissimilarity is observable between the 

 two specimens; which indeed leads to observations respecting the 

 labours of the insect, and the structure of the coral, which were they 

 not here out of place, would be right to pursue. 





