TOP. 



25 



succeed in doing so ; for the blue, having taken 

 so much pains to turn out the yellow, will not 

 entirely vacate the premises, and, coalescing with 

 the red, forms a deep purple, the red very much 

 predominating. So we have here all the primary 

 colours fighting for the dominion, and yellow, 

 the most powerful of the three, forced to retire 

 before its complementaries. 



There are great numbers of little shells, called 

 Tops from their form, which are found plenti- 

 fully on every coast, either empty and cast ashore 

 by the waves, or living, and found adhering to 

 the sea- weeds that are laid bare at low water. 

 It is not often that these shells are found quite 

 perfect, for the shell is generally worn away at 

 the apex, so that the colouring substance is 

 removed and the point of the shell is white. 

 One of the most beautiful of these shells, the 

 Livid Top (Trochus zizipMnus), is represented on 

 plate B, fig. 1. 



The tongue of this species is remarkable for 

 its structure. Many molluscs are furnished with 

 very wonderful tongues, the true beauty of which 

 can only be seen by placing them under a 

 microscope of moderate power. Their tongue 

 is easily extracted by drawing it out from its 

 hiding-place with a needle, and cutting it 



