i8 4 



UNSEGMENTED "WORMS." 



are two suckers an anterior, perforated by the mouth ; 

 a second, imperforate, a little farther back on the mid- 

 ventral line. 



There is a muscular 

 pharynx and a blind 

 alimentary canal which 

 sends branches through- 

 out the body. The 

 food is the blood sucked 

 from the liver of the 

 host. From a ganglion- 

 ated collar round the 

 pharynx, nerves go for- 

 ward and backward ; 

 of those which run back- 

 ward, the two lateral are 

 most important. Al- 

 though the larva has 

 eye spots to start with, 

 there are no sense 

 organs in the adult. 

 The body cavity is not 

 represented unless it be 

 by minute intercellular 

 spaces in the body par- 

 enchyma. Into these 

 there open the internal 

 ciliated ends of much- 

 branched excretory 

 tubes, which unite pos- 

 teriorly in a terminal 

 vesicle opening to the 

 exterior. 



FIG. 95. Structure of liver fluke. After 

 Sommer. From ventral surface. The 

 branched gut (g.) and the lateral 

 nerve (l.n.} are shown to the left, the 

 branches of the excretory vessel (e.v.) 

 to the right. 



m., Mouth; ph., pharynx; -., lateral head o nPrma f O7Oa , c bv a nair of 

 ganglion; v.s., ventral sucker; c.s. t position spermatozoa pass oy a 

 of cirrus sac. An arrow indicates the ex- ducts (vasa deferentia) into 

 cretory aperture. a seminal vesicle lying in 



front of the ventral sucker. 



Thence they are expelled by an ejaculatory duct, which passes through 

 a muscular protrusible penis. The retracted penis and the seminaj 



The reproductive system is 

 hermaphrodite and complex. 

 From much-branched testes, 



