162 



COLLEGE ZOOLOGY 



The best-known member of this order is the liver-fluke, which 

 has a fairly representative life-history. Usually the Digenea 

 occupy two, but sometimes three, hosts during their development ; 

 one host is generally a vertebrate, one a snail, and the third an 

 insect or other animal. Clonorchis sinensis and Paragonimus 

 ringeri attack human beings in China. A few Trematoda and 

 their hosts are given in Table VII. (From the Cambridge 

 Natural History.) 



TABLE VII 



THE LIFE-HISTORIES OF A FEW DIGENETIC TREMATODES 



