CH. I] 



EARTHWORMS AND LEECHES 



body to a band-like shape, 

 swims by rapid and graceful 

 undulations of its tough, mus- 

 cular body. 



Food. Blood of vertebrate 

 or invertebrate animals consti- 

 tutes the chief food: cattle, 

 birds, frogs and tadpoles, snails, 

 insects, small soft-bodied crus- 

 tacea, and worms are all attack- 

 ed by various species as occasion 

 offers. The mouth may be 

 provided with teeth as in the 

 Medicinal Leech, which pos- 

 sesses three jaws resembling 

 portions of a circular saw and 

 studded on the circumference 

 with numerous minute teeth, 

 or there may be no teeth, 

 but a protrusible proboscis-like 



Fig. 5. Hirudo medicinalis, pharynx. 



about life size. Jt hag been ghown that 



1. Mouth. 2. Posterior sucker. 



3. Sensory papill on the certain blood-sucking leeches 



anterior annulus of each seg- ,. , i , ,1 



ment. The remaining four discharge over and into the 

 annuli which make up each woun d inflicted by the teeth a 



true segment are indicated 



by the markings on the dorsal fluid which has the property 



of preventing the blood from 



clotting, so that the flow of blood is not checked while the 

 animal is feeding, and probably too solidification is pre- 

 vented in the capacious sacculated crop into which the blood 



