The creature is also known by the name of the liver-fluke, since it principally attacks this important organ in the animal.
The liver-fluke is a flat, tongue-shaped, brownish worm about an inch long and about half as wide.
The tiny freshwater snail is the host of the juvenile stages of the liver-fluke of the sheep.
Its cause is a small, flat worm—the liver-fluke—which infests the liver and bile-ducts of the affected sheep.
The history of the liver-fluke is a most complicated example of alternation of generations.