260 



ZOOLOGY 



(Fig. 202) a series of marginal tentacles are present in addition to 

 both anterior and posterior suckers. In the Aspidocotylea there is 

 only a single sucker ; but it extends over nearly the whole of the 

 ventral surface, and is complicated in structure owing to its cavity 

 being divided into a number of compartments by a system of 

 jjartitions. 



Save in two exceptional cases {Temnocephala) vibratile cilia are 



B IG. 202.— ActinodactyleUa. h. c. bursa copulatri.x ; hr. brain 

 ovary; ph. pharynx; r. ». receptaculum ; s. sucker; «., 

 glands ; v. s. vesicula seminalis. 



penis ; l. intestine ; ov. 

 ut. uterus ; v. vitelline 



not known to occur on the surface in the adult condition ; in some 

 there are groups of non-motile cilia, situated on little conical 

 elevations — the tacfAle cones. Pigment is rare in the endoparasitic 

 Digenetica, save in a few that live in the interior of transparent 

 animals ; though many appear coloured variously by the internal 

 organs shining through the translucent body-wall, or are stained 



