CHAPTER THIRTY-TWO 



NEMERTINEA 



I. THE nemertean worms are little "known to the Characters 

 general public, as they are of slight economic impor- *J* 

 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 Linens 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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