130 EXPLANATION OF THE FIGURES. 



witli fig. 6 a; figs. 5 e, 5/, and 5^, are fuU-growii 

 individuals, found in the liver of the fresh-water 

 snau. 



Fig. 6. Large " nursing'' individuals, in which the Bis- 

 toma-larva are already become pupae, and have at- 

 tained their full development. Fig 6 «, a " nurse" 

 in which a fuUy developed Distoma tarda may he 

 seen among a crowd of fully and half developed 

 larvce. Fig. 6 5, a similar " nurse" v^ith four such 

 Bistomata, which are placed alternately on the op- 

 posite sides. 



Figs. A, B, C, The Echinorhynchus of the sole, in a 

 young state. 



Fig. a. An echinorhynchus, inclosed in a thick, mem- 

 branous cyst. Fig. B, the same extracted from the 

 cyst. Fig. C, the same with its proboscis protruded. 



