Figure 15,--Skin ulcers in young herring caused by underlying 

 muscle infection with the myxosporidian. Kudoa dupeidae. 



METACERCAfllA ENCYST 



BENEATH SKIN CAUSING 



PIGMENT SPOT 



CERCARIAE DEVELOP IN REDIA 

 AND EMERGE FROM SNAIL 



REDIAE DEVELOP 

 I SNAIL DIGESTIVE GLAND 



Figure 16a.--Life cycle of CryptocotyU lingua, the worm whose larvae cause '•pigment spot" of herring and other fish, 



Figure 16b.--Pigment spot of herring caused by CryptocotyU 



lingua. 



12 



