PL A T YHELMINTHES. 



137 



CHAPTER XIV. 



FLAT YHELMINTHES, ROTIFERA AND 

 NEMATHELMINTHES. 



DISTOMUM. 



HYDATINA. 



I.— DISTOMUM. 



Phylum *- 

 Class 



Platyhelminthes. 

 Trematoda. 



Fig. 69. — Ventral View of Liver-Fluke {Dislomuvi hepatiaivi). 



Natural size. {Ad nat.) 



Anterior Sucker 

 and Mouth. 



Posterior' ,~ 

 Sucker. 



(Esophagus. 



A, Exterior. 



B, The AHmentary System. 



Distomum hepaticum is the liver-flake of the sheep. 

 It may grow considerably over one inch in length and shows 

 a flat leaf-like shape. It is piano-symmetric and flattened 

 dorso-ventrally. 



It infests the liver and bile-ducts of the domestic sheep, 

 and causes the disease called " liver-rot " which is fatal to 

 great numbers of sheep. Obstruction of the bile-duct by 

 hundreds of these parasites causes inflammatory processes 

 and bleeding of the liver-tissues. General wasting and often 



