p. 239 



Fig. 261. Diagram of the distribution of certain species of 

 Dactylogyrus on cyprinid fishes which hybridize among them- 

 selves. The lines between separate species of fishes indicate 

 that these fishes hybridize with each other. 

 l--Chondrostoma nasus (L,. ); 2-- Leuciscus cephalus (L. ); 

 3--L,euciscus leuciscus (L. ); 4-- Vimba vimba (L. ); 

 5--Blicca bjoerkna (L. ); 6--Chalcalburnus chalcoides (Guld. ); 

 7--Abramis brama (L. ); 8--Alburnus alburnus (L. ); 

 9--Scardinius erythrophthalmus (L. ); 1(D-- Rutilus rutilus (L. ); 

 ll-- Rutilus frisii (Nordm. ). 



a--Dactylogyrus sphyrna Linstow; b- -D. cornu Linstow; 

 C--D. nanus Dogiel et Bychowsky; d--D. crucifer Wagener; 

 e--D. difformis Wagener; f--D. similis Wagener. The symbols 

 of species of parasite filled with black color indicate that the 

 parasite is predominantely encountered in that particular fish. 



266 



