APPENDIX A 161 



34. 8-10 crescent-shaped ocelli on posterior sucker; gono- 

 pores separated by 2 annuli; sperm duct convoluted. 



Piscicola salmositica Meyer 1946 



— 10-12 punctiform ocelli on posterior sucker; 2 annuli 

 between gonopores; sperm duct simply looped. 



Piscicola milneri (Verrill 1871) 



— 12-14 punctiform ocelli on posterior sucker; 3 annuli 

 between gonopores; sperm duct simply looped. 



Piscicola geometra (L.) 



35. American species. Cystohranchus verrilli Meyer 1940 



— European species 36 



36. Eyes absent from anterior and posterior suckers; no 

 distinct copulatory area. 



Cystohranchus mammillatus (Malm 1863) 



— 4 eyes on anterior sucker and 10 ocelli on posterior 

 sucker; a well marked copulatory area (Fig. 12) . . . . 37 



Fig. 12. Anterior portion of Cystohranchus fasciatus, ventral 

 view, to show copulatory area (shaded). After Autrum. 



37. Diameter of anterior sucker nearly twice the greatest 

 width of anterior body region. 



Cystohranchus fasciatus (Kollar 1842) 



— Diameter of anterior sucker about the same as the 

 greatest width of the anterior body region. 



Cystohranchus respirans (Troschel 1859) 



38. 3 annuli per segment; no clear division between 

 anterior and posterior body regions. 



Piscicolaria Whitman 1889 

 One species, P. reducta Meyer 1940 



