no setae; body usually stout; scmi'parasitic animals, often found free 2. 

 No sucker on the posterior end; with setae; body usually slender 40. 



2. No sucker on the anterior end; parasitic on crayfishes; Family Discodrili' 



dae or Branchiohdellidae of Class Oligochaeta 3. 



With a sucker on the anterior end; Class Hirndinea or Leeches 10. 



3. Back with projections or raised cross bars 4. 

 Not so 5. 



4. Back with rough, raised, cross bars 



Cirrodrilus Pierantoni 

 With large, upright projections along the mid-dorsal line 

 Pterodrilus Moore 



5. Posterior end flat and wide, so that the body is spadc'shaped 



Xironogiton Ellis 

 Not so 6. 



6. Body flattened; posterior sucker on the under side of body 



yiironodrilus Ellis 

 Body cylindrical; posterior sucker at the end of body 7, 



7. With most of the main body segments subdivided into three rings 



Triannulata Goodnight 

 Not so 8. 



8. Head very distinct from the body; with one pair of testes in segment five 



Branchiohdella Odier 

 Head less distinct from the body; with two pairs of testes in segments five 

 and six 9. 



9. Head narrower than first body segment 



Bdellodrilus Moore 

 Head as wide as or wider than first body segment 

 Camharincola Ellis 



10. Mouth filling most of the cavity of the anterior sucker; no proboscis 11, 

 Mouth only a tiny hole in the anterior sucker, from which a proboscis 



may be projected 22. 



11. Without eyes or with three or four pairs of minute eyes not in cresdentic 



arrangement; without jaws — Family Herpohdellidae or Worm Leeches 



12. 



With five pairs of tiny eyes in crescentic arrangement around the anterior 



end; usually but not always with three jaws, which are often difficult 



to see — Family Hirudinidae or Blood Suckers 15. 



12. Body regularly ringed 



Herpohdella punctata (Leidy) Common Worm Leech 

 With each fifth or sixth body ring enlarged 13. 



13. With four pairs of eyes; back blotched or plain dark colored 



J^lephelopsis ohscura Verrill 

 With three or four or no pairs of eyes; back lengthwise striped or al* 

 most without pigment and appearing pinkish 14« 



14. With lengthwise stripes 



Dina anoculata Moore 

 Pinkish 



Dina fervida (Verrill) 



86 



