316 



EVENINGS AT THE MICEOSCOPE. 



merits : — Whence we may compute the total number of 

 prehensile comb-like plates on this portion of the body 

 to be about one thousand nine hundred, each of which 

 is wielded by muscles at the will of the animal ; while, 

 as each plate carries on an average five teeth, there are 

 nearly ten thousand teeth hooked into the lining mem- 

 brane of the cell, when the animal chooses to descend. 

 Even this, however, is very far short of the total num- 

 ber, because long ribbons of hooks of a similar struc- 

 ture, but of smaller dimensions run across the abdo- 

 minal 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 ! 



EOOKa OF SERPULA. 



