VOLUTES. 81 



varying slightly in different individuals of the same species, 

 and even exhibiting four or five strong plaits, with several 

 finer rudimentary plaits in addition. 



Somewhat of inconstancy pertains also to the form of the 

 Volute ; the same species being at one time elongately con- 

 voluted, with the spire proportionably exserted ; at another, 

 shorter and contracted, as also either smooth or tubercled, 

 just as a Cone is smooth or granulated ; and the closer and 

 more contracted the growth of an individual, the thicker 

 and more prominently is the shell raised in tubercles. 



^' The most decided characteristics for the distinction of 

 species are to be found in certain parts of the shell, such as 

 the apex and the base, with the general contour' of the 

 body-whorl, and its texture and substance, the outline of 

 the aperture, and, above all, in the general design of paint- 

 ing. However much a species may differ in its plan of 

 convolution, the parts referred to are the same ; and how- 

 ever variable a species may be in colour, there is but 

 one idea in its pattern and manner of distribution. There 

 is more constancy in the pencil of the Yolute than in the 

 colours of its palette.''^ 



In most species the apex is blunt and papillary ; that is, 

 the first two or three whorls, constituting the nucleus of the 



G 



