worms. 275 



will of the animal ; while, as each plate carries on an 

 average five teeth, there are nearly ten thousand teeth 

 hooked into the lining membrane of the cell, when the 

 animal chooses to descend. Even this, however, is very 

 far short of the total number, because long ribbons of 

 hooks of a similar structure, but of smaller dimensions, 

 run across the abdominal segments, which are much more 

 numerous than the thoracic. No wonder, with so many 

 muscles wielding so many grappling hooks, that the retreat 

 is so rapidly effected ! 



t 2 



