Plate XX. 



T R I s T M U M S I N U A T U 31 . 



Fig. 1. The wliüle worm viewed from the ventral side. The vitellarinm is re- 



presûiitctl only on one side, and the nervous and excretory systems on the 



other. Nervous system shaded with parallel lines ; excretory system 



shaded darkest. 

 „ 2. One of the hooks of the posterior sucker, x 204 diam. 

 „ 3. Chitinous corpuscle at the opening of the lateral gland, x 201 diam. 

 „ 4. Three elevations of the posterior sucker at the point of their junction, 



in a surlixce view, x 204 diam. 

 J, 5. Cross-section of the posterior sucker through its stalk, x 29 diam. 

 „ G. A small portion of the radial section of the posterior sucker transversely 



to the long axis of the body, x 204 diam, 

 ,, 7. A small portion of the tangential section of the posterior sucker, x 73 



diam. 

 „ 8. A portion of the cross-section of the body at the level of the oesophagus, to 



show the salivary glands, x 73 diam, 

 ,, 9. Two cells of the salivary gland, x 427 diam. 

 ,, 10. A portion of the cross-section of the anterior sucker uf the right side and of 



the adjoining part of the body, x 204 diam. 



