DESCRIPTION. 187 



marine insects, we need not hesitate to pronounce 

 wliat it is not; what it really is, must still remain 

 to be determined. The calcareous matter of which 

 it is composed seems to be agglutinated in a dif- 

 ferent manner from that of Madrepores and Corals, 

 to which it bears the most remarkable resemblance. 

 The olive-green spots, which are often raised above 

 the yellowish white surface, appear of the same 

 construction with it, and are not regularly stellated, 

 or more deeply pored. The arms are solid, and 

 penetrated with the green colour in spots through- 

 out. These processes vary in different specimens 

 both in number and in length. The aperture is 

 distinctly of the same shape as that of a Turbo, and 

 hence the opinion may have arisen that the whole 

 is parasitically formed by a coral insect which takes 

 a certain species of Turbo for its nucleus. In op- 

 position to this it may be stated, that there is no 

 outward appearance of spire beyond the first whorl; 

 that the aperture bearsevery mark of the recentpas- 

 sage of an inhabitant, being smooth, and free from 

 all obstruction. That there is indeed no foreign 

 shell is plain, from the circumstance of the sub- 

 stance being of the same nature in every part, 

 and the inside of the outer lip showing the foun- 

 dation of the spots through a thin slimy covering. 



