596 DR. p. E. BEDDARD ON 



The excretory vessels consist of the usual dorsal and ventral tubes 

 running continuously through the strobila. Anteriorly there is 

 less difference in the calibi-e of these tubes than posteriorly. The 

 position in relation to each other also becomes altered. In immature 

 segments (where I have studied the excretory tubes) the rather 

 smaller dorsal vessel lies obliquely above the ventral vessel to the 



Text-fig-. 80. 



\ 



^.X~-- -X^cl.v 



'%> 



Xt; 



Syracottsnia hyracis. 



Transverse section through a proglottid. 



d.v. Dorsal excretorj^ tube. T. Row of testes. V. Vitelline gland. 

 v.v. Ventral excretory tube. 



pore side of the same. In maturer proglottids the tvs^o vessels are 

 practically superposed, and the dorsal vessel is at times so minute 

 as to escape observation. Both of these vessels are connected 

 with a network of larger and smaller water vascular capillaries 

 which traverse the medullaiy region of the body. I have seen 

 branches of these ending in a testis, and it becomes a matter of 



