A SURVEY OF THE GROUP 



27 



in Fig. 16. There are longitudinal dorsal, ventral, and lateral 

 sinuses, transverse subcutaneous sinuses, and various intermediate 

 connecting sinuses. The dorsal sinus is almost completely filled 



Dorsal connecting sinus 



Intermediate sinus 



Lateral sinus^ 



Subcutaneous sinus 

 Dorsal vessel 

 Dorsol sinus 

 Ventrol sinus 



Ventral vessel 



Ventral connecting sinus 



Ventral nerve cord 



Fig. 16. Reconstruction of part of the coelomic sinus system 

 of Glossiphonia cojnplanata. After Oka, 1894. 



by the dorsal contractile blood vessel; the ventral contains the 

 ventral nerve cord, the ventral vessel, and the female genital organs, 

 as well as the funnels of the nephridia in certain segments. Chlora- 

 gogenous cells are present, adhering to the walls of the sinuses or 

 floating freely in the coelomic fluid. The parenchyma between 

 the coelom and the body wall contains many conspicuous adipose 

 cells and pigment cells. 



The dorsal blood vessel is equipped with fifteen sets of valves 

 and by its contraction drives blood forward. A number of capil- 

 laries connects the dorsal and ventral vessels anteriorly, so that 

 blood is forced backwards through the ventral vessel. It then 

 travels through the capillaries of the posterior sucker, and up into 

 the dorsal vessel again. In the region of the intestine the dorsal 

 vessel has four pairs of lateral caeca which lie very close to the 

 intestinal caeca. 



Other members of the Glossiphoniidae include parasites of fish, 

 water birds, reptiles and Amphibia. Hemiclepsis marginata (Fig. 17) 

 is chiefly a fish parasite, although it may also attack tadpoles and 



