166 



LEECHES 



55. 



56. 



57. 



In any group 6 consecutive annuli at least 1 is different 

 from the rest, being either much narrower or wider 



and subdivided 56 



Genital pores separated by 2-3^ annuli; typical forms 

 with a broken network of black pigment on the dorsal 

 surface. Erpobdella octoculata L. 



Genital pores separated by 3|-5 annuli; typical forms 

 lack black pigment dorsally, less common varieties may 

 have a median dark line or a transparent body revealing 

 deep lying black pigment. 



Erpobdella testacea (Savigny 1820) 

 A group of 5 consecutive annuli consists of 4 of equal 

 width and 1 which is wider but divided by a faint trans- 

 verse furrow (Fig. 19); genital pores separated by 2-3 

 (or 3 1) annuH. Dina E. Blanchard 1892 57 



Fig. 19 



Fig. 20 



Fig. 19. Ventral view of segment XII of Dina lineata to 

 show genital pores and annulation. 



Fig. 20. Ventral view of segment XII of Trocheta bykowskii 

 to show genital pores and annulation. 



The most common arrangement of annuli is 3 broad 

 and 5 narrow (Fig. 20) but the narrow annuli may be 

 associated in pairs forming broad annuli faintly sub- 

 divided or each broad annulus may be divided to form 

 2 narrow ones; there are many arrangements, all of 

 which differ from those found in the other Erpobdellidae. 



Trocheta Dutrochet 1817 

 Eyes present, number and position variable. 



Dina lineata (O. F. Muller 1774) 



58 



