260 



ZOOLOGY 



SECT. 



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

 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 

 partitions. 



Save in two exceptional cases (Temnocephala) vibratile cilia are 



Fig. 202.— Actinodactylella. 6. c. bursa copulatrix ; br. brain ; c. penis ; i. intestine ; ov. 

 ovary; p}i. pharynx; r. v. receptaculum ; s. sucker; t., t. testes; ut. uterus; v. vitelline 

 glands ; v. s. vesicula seminalis. 



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 tactile 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 



