AVIAN CESTO])ES. 



595 



The water-vascular tubes of this worm present no remarkable 

 characters. The much larger ventral vessel is alone present, in 

 the posterior segments. Anteriorly both tubes are visible and 

 superposed. The transverse trunks unite the ventrals in each 

 segment. The usual valvular flaps in the ventral vessel are 

 obvious and attached, as is usual (but not universal), to the inner 

 wall of that tube. 



Text-fiffure 3. 



T, L, 



\ r 



f 





^^ 









"1* » 











« « 



* « 



» 



Part uF a transverse sectiou througli a proglottid in the posterior region of 

 the body. 



Letterint;- as in text-fig. 2. 



The male and female efferent ducts open into a cloaca genitalis 

 which is not specially deep. The genital pores are completely 

 unilateral in this species, aud somewhat anterior in position, at 

 any rate in front of the middle line of the lateral border. I have 

 found so many orifices in succession opening on to one side 

 of the body, that I cannot believe that the conditions are for 

 instance as in Cha'pmania taaricollis, where the orifices really 



