mth 



Q.p <' 



B 



XXIV 



XXV 



Fid. 411. Hirudo medicinalis. A, dorsal ; B, ventral aspect ; a. anus ; a. s. anterior sucker; 

 e. 1. first, and e. 5. fifth pair of eyes; g. p. <S . male gpnopore ; g. p. 9. female gonopore; 

 mth. mouth ; np. 2. first, and np. 17. seventeenth pair of nephridiopores ; p. s. posterior 

 sucker ; *. p. segmental papilUe ; I. XXVI. segments. 



