TOP- SHELL 7 



some shelled mollusk, the Purple-spotted Top. 1 Before 

 we take him up, let us notice for a moment with what 

 an easy even movement he glides along over the leaves 

 of the sea-weed, now over the stony projections of the 

 pool, now on the broad weeds again. On lifting the 

 shell, we find that the fine, fleshy, apricot-coloured 

 animal clings with considerable force to the weed ; and 

 on transferring it to a glass bottle, we get a better sight 

 of the organ by which it maintains both its stability 

 and its movements. The under-surface of the creature, 

 then, forms a long, nearly parallel- sided sole, abruptly 

 pointed behind, where it stretches to a considerable dis- 

 tance in the rear of the shell, and bounded in front by 

 a slightly- thickened transverse rim, a little arched, and 

 projecting on each side. This organ is the foot, and it 

 is composed of muscular fibres elaborately interwoven, 

 much as in the human tongue, whereby great versatility 

 and power of motion are communicated to it ; indeed, 

 when in motion, it strongly reminds one of the human 

 tongue. 



The sensitive and muscular foot of our captive has 

 already taken hold of the glass side of its prison, and 

 it is now smoothly mounting up it. With a lens you 

 may see that though it is one undivided area, yet in 



1 Trochus ziziphinus, which the reader will see figured in the upper 

 right corner of Plate I. 



