202 



ELEMENTARY ZOOLOGY. 



two sucking discs whereby they may attach themselves 

 to the host. They have a peculiar enlargement of the 

 digestive tract that enables them to swallow large amounts 

 of blood on which they may live for many days (Fig. 61). 



FIG. 60. Cirratulus grandis, from Verrill. 



Questions on the Figure. What evidence have you that this is 

 a chaetopod? Compare this form with the preceding at all points. 



219. Non-sexual Reproduction and Regeneration of 

 Lost Parts. Many of the worms, both of the marine and 

 fresh-water kinds, have the power to develop into two 

 or more worms by producing a new tail and head in the 

 middle of the body. This usually takes place in one 

 segment ; the anterior half of it makes a tail for the forward 

 worm and the posterior makes a head for the hinder one 

 (Fig. 58) . They may remain together until a chain of 

 four or more have formed. They finally separate and 



