362 MANUAL OF NATURAL HISTORY. 



III. ORDER SUCTORIAL-WOKMS (Trematoda). 



Body flattened, more or less oval, with one or 

 more prehensile disks on various parts ; mouth ter- 

 minal, in form of a circular sucking disk. 



1. FAMILY. Flukes -proper (Fasciolidas). Mouth 



with a single terminal sucker ; body soft, 

 oblong, depressed, tapering, with posterior 

 ventral prehensile disk. 



2. FAMILY. Diplostome - Flukes (Diplostomidae). 



Mouth with a single terminal sucker, body flat 

 or sub-cylindrical, with two suckers on lower 

 surface, and a purse-like appendage at hind part. 



3. FAMILY Fringed - Flukes (Caryophyllidse). 



Mouth bilabiate, surrounded by a fimbri- 

 ated, contractile, dilated disk; body soft, 

 elongated, tapering posteriorly. 

 4 FAMILY. Tailed-Flukes (Cercariidse). Mouth a 

 simple suctorial disk, with a smaller sucker 

 behind it ; body with a long posterior caudal 

 appendage, which can be readily cast off by 

 the animal. 



5. FAMILY. Proboscidean-Flukes (Tetrarhynchidae). 



Head with four retractile proboscidiform 

 suckers ; body sack-like, subclavate, anteriorly 

 obtuse, tapering behind. 



6. FAMILY. Eared-Flukes (Scolecidse). Mouth ter- 



minal, encircled by four plicate, sub-perforate, 

 ear-like suckers ; body gelatinous, elongate, 

 sub-depressed, contractile, anteriorly clavate, 

 posteriorly acuminate. 



