A N > ULOIDA SCOLECIDA. 



81 



water, by the movements of the cilia with which their 

 bodies are furnished. The best known group are the 

 planaria (Gr. plane, wandering). They are small, flat- 

 tened animals, with soft, black, gelatinous flesh. They 

 are found in great abundance in. rivers and ponds, attached 

 to submerged plants. Other larger species belong to the 

 sea shore. The mouth is placed near the centre of the 

 body. The digestive canal has only one opening. The 

 skin is furnished with numerous cilia. There are two 

 nervous ganglia placed near the mouth, connected by a fila- 

 ment. They possess a number of rudimentary eyes, which 

 are situated on the front part of the 

 body. There is a water vascular 

 system which communicates with the 

 exterior. 



The nemertes or ribbon-worms also 

 belong to this group. They are found 

 on the sea shore coiled up in knots 

 under stones, arid are sometimes ninety 

 feet long. The alimentary canal has 

 two openings. The water vascular 

 system in the adult seems to have no 

 communication with the exterior. 



116. Trematoda (Gr. trema, an open- 

 ing) or flukes are internal parasites in- 

 habiting the bodies of man, sheep, birds, 

 and fishes. They are somewhat flat in 

 shape, and are furnished with one or 

 more suckers, by which they attach 

 themselves to the bodies of their victims. 

 One of these suckers leads into the 

 mouth, and is succeeded by a branched 

 alimentary canal, which has no anal 

 opening. There is also a branched 

 water vascular system, which communicates with the 

 exterior. The best known of these animals infest the gall 

 bladder or the liver of the sheep, producing the disease 

 called rot. 



15 E, F 



