MUREX ROCK SHELL. 93 



tubercles, foliations, or varices ; aperture oval 

 ending in a beak, either straight or turned 

 backwards. Some of the species are remarka- 

 ble 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 genus has caused them to be ar- 

 ranged under several divisions ; but the mark 

 by which a Murex, according to the Linnaean 

 definition, may be easily recognised, is the oval 

 shape of the mouth ; this being preserved even 

 when the aperture is terminated by a beak, as 

 instead of gradually contracting, it abruptly 

 opens into a canal. Besides this regularity in 

 the outline of the aperture, another distinctive 

 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 folia- 

 tions ; and from the rock-like and rugged ap- 

 pearance thus occasioned they derive their desig- 

 nation. Some of the shells of this genus are 

 remarkable for the singular extension of their 

 beak. 



Many of the Murices are distinguished by 

 their thick protuberent rounded varices. These 

 shells have been divided into different genera 



