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 pro- 
portional deflection from the straight line would be occasioned ; and a 
coralline body of a curved form be produced. Specimens of both these 
forms, it has been just remarked, are frequently found. 
The appearances yielded by two sections of this species of madreporite 
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 concentric 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. 
