Annulata. 



9 1 



travel with the pos- 

 terior end fore- 

 most, as it does 

 occasionally, it has 

 but to point the 

 spines forward, 

 and the same action 

 of the muscles will 

 propel it posterior 

 end foremost. If 

 the worm were 

 lying on a perfectly 

 smooth surface, on 

 which there was 

 no friction what- 

 ever, the shorten- 

 ing and lengthen- 

 ing of the body 

 would avail noth- 

 ing in the way 

 of locomotion ; it 

 would be simply 

 motion. The loco- 

 motion of the earth- 

 worm, however, is 

 not essentially 

 different from that 

 of other animals, 

 they must all 

 have some point of 

 support or resist- 

 ance by means of 

 which they pro- 



