NEMKRTINBA 



39 



latus, from eating fish. The latter species is the largest tape- 

 worm found in man and sometimes reaches a length of 40 feet, 

 and is composetl of more than four thousand proglottides. It 

 is rare in America, but is abundant in Russia, Switzerland, and 

 the eastern provinces of Prussia. Another form (Fig. 28), 

 perhaps the most formidable, is a small one, Ta'nia ecJmiococ'cus, 

 which lives, in the adult stage, in dogs (Fig. 29), and the eggs 

 are easily taken into the human stomach by a person fondling 

 and kissing infested dogs. The embryos (Fig. 30), when set 



Fig 30. — Portion of hog's liver infested with echinococcus bladder-worm. 



(Stiles.) 



free, work their way into the liver, lungs, brain, or other organs, 

 and produce tumors which sometimes reach a large size. Several 

 species are found in domestic birds, one causing epidemics 

 among chickens. A variety of Tce'nia cocnu'rus, in the brain of 

 sheep, causes " staggers." Rabbits, horses, cats, mice, and 

 rats are also infested by tapeworms. 



CLASS IV. NEMERTINEA 



(Doubtful Platyhelminthes) 



The Nemertineans are most abundant in the mud or under 

 stones along the seashore, only a few species living in fresh 

 water. They differ from all other Platyhelminthes in having 



