182 GENERAL ZOOLOGY 



verted scolex on one side. If it gets into a man's intestine, 

 the scolex is pushed out (F), fastens its suckers on the wall 

 of the intestine and soon begins to bud off proglottids. 

 About 1 per cent, of all the cattle slaughtered in the 

 United States have tapeworm larvae in their flesh, and there 

 is another species which frequently infests pork. Any of 

 these larvae will be killed if meat is thoroughly cooked. A 

 piece of meat if boiled should be cooked about fifteen min- 

 utes for each pound. 



PHYLUM NEMERTINA 



The nemerteans resemble the flatworms in their general 

 form but are more specialized in many respects : an anus is 

 present, the mouth is at the anterior end, there is a retrac- 

 tile finger-like proboscis above the mouth, a definite cir- 

 culatory system is present for carrying blood. Some 

 nemerteans are of large size, attaining a length of ninety 

 feet. Most species live along the seashore, but a few are 

 found in fresh water and on land. 



