82 HALF AN HOUB WITH SEA-WORMS. 



observed, than the former. The rainbow colours 

 which seem to chase each other as it throws itself 

 into the most graceful curves, in order to adjust itself 

 to the inequalities of the rock, and the pearly flesh- 

 colour of the under parts, render it really a charming 

 object. If you disturb it gently you will notice a 

 remarkable change come over it. The under side of 

 its head rises from the ground, swells, and then 

 seems to turn itself inside out. Presently a great 

 pear-shaped bag is protruded, eight times as long 

 and three as broad as the entire head. The surface 

 of this new organ is rough, and small rows of 

 tubercles may be seen clustering round the ex- 

 tremity. This peculiar apparatus is called the 

 " proboscis," and is supposed to be used for the cap- 

 ture of its prey. Finally, we must notice another 

 sea-worm, by far the most repulsive and ugly of the 

 whole class. This is the Nemertes. It appears like 

 a long, thin, black cord, entwined round any object 

 it can get, and so far greatly resembling a miniature 

 serpent. This likeness is further carried out in its 

 head, which is remarkably snake-like. It is a 

 deadly foe to the tubed- worms, such as the serpula 

 and sabella, which it literally drags out of their 

 retreats to devour. 



Lastly, let us briefly draw attention to a common 

 species of sea-worm which constitutes a group by 

 itself. This is the Sipunculus, a creature remarkable 

 for its appearing to connect the " sea-cucumbers " 

 with the Annelida. In shape it is not at all unlike 



