DISTOMUM HEPATICUM 



II 



The sporocyst has an external cuticle, and beneath this an 

 external circular and an internal longitudinal layer of muscle 



Stages in the life-history of DistoTnum hepaticnm. i. An egg filled with large 

 vitelline cells, in which the segmenting ovum, em, is embedded ; o, oper- 

 culum. 2. Miracidium larva, showing the large ciliated cells,' the eyespot 

 e, and the interior papilla, pa. 3. A miracidium boring its way into the 

 tissues of a Limncea ; /■/, flame-cells. 4. A sporocyst containing one fully 

 developed and several developing redias. The degenerate eyes are shown at 

 e. 5. A redia containing several daughter redias in various stages of develop- 

 ment; ?;?, mouth; />h, pharynx; ent, enteron ; ?-, muscular collar; p, 

 posterior processes. 6. A cercaria ; in. mouth ; s', anterior, and^", posterior 

 suckers; cs, cystogenous cells. (After Thomas.) 



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