136 



DISTOMA HEPATIC UM, Linn. 



Plate XVI. 



Fig. 1. Adult fluke, natural size : la, young fluke, natural size. (Eaillet.) 



Fig. 2. Eggs: a, egg with developing embryo; b, egg with embryo; c, egg-shell. 

 (Eaillet.) 



Fig. 3. Ciliated and free embryo : a, perforating apparatus ; 6, ocular spot. (Leuck- 

 art.) 



Fig. 4. Encysted embryo found in snails. (A. P. Thomas.) 



Fig. 5. Diagram of digestive apparatus and nervous system : a, mouth sucker; J, 

 pharynx; c, oesophagus; d, branches of intestine ; e, their brauchlets ; 

 , /, nerve ganglia ; (7, ventral nerve. (Riiillet.) 



Fig. 6. Limnwus truncatulus, the principal snail which is the larval host of the fluke 

 in Europe: o, natural size. (Eaillet.) 



Fig. 7. Eedia of Distoma hepalicum : a, mouth; 6, pharynx; c, digestive tube; d, 

 the so-called germinati ve cells destined to produce ccrcariae. (Leuekart. ) 



Fig. 8. Eedia containing cercariae: a, mouth; 6, pharynx ; c, digestive tube; d, d, 

 cercarise. (Leuekart.) 



Fig. 9. Cercaria dissected from its cyst : a, anterior sucker ; 6, ventral sucker ; c, 

 pharynx; dri, branches of the intestine terminating in casca. (Leuekart.) 



Fig. 10. Grass stalk with three encysted young flukes, a, a. (A. P. Thomas.) 



Fig. 11. Free-swimming cercaria just before itisabout to encyst. (A. P.Thomas.) 



Fig. 12. A slightly older stage than Fig. 11. (A. P. Thomas.) 



Fig. 13. Genital apparatus of the liver fluke : a, digestive tube ; b, ventral sucker ; 

 c, anterior testicle; d, its deferent canal ; e, posterior testicle ; /, its def- 

 erent canal; g, seminal veside ; h, genital sinus; i, cirrhus pouch ; y, 

 ovary; fc, oviduct; /, shell-gland; m, yolk glands ; n, longitudinal and 

 0, transverse yolk-gland canals ; p, uterus; (/, vagina. (Eaillet.) 



