Fig. 17. (a)-(g) various Glossiphoniidae. (h) a piscicolid 

 leech, (a) Helobdella stagnalis; (b) Hemiclepsis marginata; 

 (c) Glossiphonia heteroclita; (d) ventral view of Helobdella 

 carrying young; (e) Glossiphonia after rolling into a ball; 

 (f) Theromyzon tessulatwn starving; (g) T. tessulatiim after a 

 meal ; (h) Piscicola geometra. 



