DISTOMUM HEPATICUM 



ii 



The sporocyst has an external cuticle, and beneath this an 

 external circular and an internal longitudinal layer of muscle 



4- 



Fig. 2 



Stages in the life-history of Distomum hepaticum. 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 

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

 tissues of a Limntea ; f-f, flame-cells. 4. A sporocyst containing one fully 

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

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

 ment; in, mouth; ph, pharynx; ent, enteron ; r, muscular collar; />, 

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

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



