MUREX ROCK SHELL. 93 



cles, foliations, or varices ; aperture oval ending 

 in a beak, either straight or turned backwards. 

 Some of the species are remarkable for the great 

 length of the beak. 



OBSERVATIONS ON THE SHELL AND ITS 

 INHABITANT* 



The very great variety which occurs in the 

 shells of this genius has caused them to be ar- 

 ranged by modern conchologists under several 

 divisions ; the mark by which a Murex, according 

 to the Linneean definition, may be easily recog- 

 nised, is the oval shape of the mouth ; this is 

 preserved even when the aperture is terminated 

 by a beak, as instead of gradually contracting, it 

 abruptly opens into a canal. Besides this regu- 

 larity in the outline of the aperture, another dis- 

 tinctive mark is that the beak neither inclines to 

 the right nor to the left. 



The Murices are in general of an irregular form, 

 arising from their surfaces being covered either 

 with spines, tubercles, varices, or foliations ; and 

 from the rock-like and rugged appearance thus 

 occasioned they derive their designation. 



Some of the shells of this genus are remark- 

 able for the singular extension of their beak : 

 others are distinguished by their thick protu- 

 berent rounded varices : and they have been divi- 

 ded into different genera according to the arrange- 



