156 



LEECHES 



Fig. 8 



Fig. 6-8. Dorsal views of the heads of various leeches to 



illustrate eye arrangement: 6, HemiclepsiSy 7, Helohdella 



showing chitinous scute; 8(a)-(d) variations in the eyes of 



Glossiphonia complanata. 



12. A horny scute present dorsally about one-sixth of the 

 distance from the anterior to the posterior sucker. 



H. stagnalis (L.) 



— No dorsal scute present 13 



13. Body cylindrical, very slender, translucent, colourless; 

 only one pair of crop caeca. H. elongata (Castle 1899) 



— Body moderately flattened, wider posteriorly ; normally 

 6 pairs of crop caeca but some may collapse when 

 empty 14 



14. Tubercles absent or limited to mid-dorsal line of 

 posterior segments; colour coffee brown with 6 or 7 

 white spots on every third annulus. 



H. fusca (Castle 1900) 



— Tubercles absent or nearly so; with prominent longi- 

 tudinal brown stripes and transverse rows of white 

 spots. H. punctata-lineata Moore 1939. 



— Tubercles small, smooth and conical, deeply pigmented 

 and often double ; many fine longitudinal light and dark 

 lines, no large white spots. H. lineata (Verrill, 1874) 



[G. fusca (Castle) part] 



