CHAPTER THIRTY-TWO 



NEMERTINEA 

 I. THE nemertean worms are little known to the Characters 



iii- i r i i and habits 



general public, as they are of slight economic impor- of neme r- 

 tance. They mostly live in the sea, burrowing in mud teans 

 or sand, or hiding under stones and among the holdfasts 

 of large seaweeds. Fresh-water and even land forms 

 have been found, the latter living in moist earth or de- 

 caying vegetable matter. There are even a few para- 

 sitic or semiparasitic forms, though nemerteans in 

 general live independently. The great majority are 

 long and more or less cylindrical, and, as in the Tur- 

 bellaria, the skin is ciliated and the body is unseg- 

 mented. There is, indeed, much resemblance to the 

 flatworms, but the alimentary canal has two openings 

 (as in all the higher worms) instead of one. The mouth 

 is furnished with a remarkable proboscis which is capa- 

 ble of being everted. The sexes are usually separate, 

 whereas the flatworms are hermaphroditic, with very 

 few exceptions. Some of the marine species attain 

 extraordinary lengths ; the threadlike Lineus is said to 

 reach a length of 27 meters. Others are beautifully 

 colored, - - bright red, orange, or pink, or purplish with 

 white cross lines. They are carnivorous, attacking any 

 animals which are not too large. 



NEMATHELMINTHES 



i. The Nemathelminthes are the threadworms; the structure of 

 scientific name is only the English one in Greek. They 

 have the usual wormlike shape, --cylindrical, not flat, 

 and without visible segmentation. The group in gen- 

 eral is parasitic, but small forms may be found com- 



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