PLATE CXXXIII. 



Those prevailing distinctions may with propriety be considered 

 as sufficiently indicative of two distinct species ; but if any further 

 proof were wanting to establish their dissimilitude, the structure and 

 the colour of the aperture of the mouth of the shell, would afford us 

 all the character required ; the pillar; as well as the lip of 

 H. Haemastoma being of a rich crimson colour, and thus forming a 

 deep red border round the mouth, while that of Melanotragus is pur* 

 plish, verging to an intense black in the darker shades ; or in other 

 words, has the mouth bordered with black instead of red, Th§ 

 inside of the shell is white. 



