“ In systematic zoology, however, the use of a division Vermes has been abandoned, as it is now recognized that many of the animals that even a zoologist would describe as worms belong to different divisions of the animal kingdom. The so-called flatworms (Platyelmia, q.v.) , including the Planarians (q.v.) . Flukes (see Trematodes) , Cestodes (see Tapeworm) and the curious Mesozoa (q.v.) , are no doubt related. The marine Nemertine worms (see Nemertina) are isolated. ”

“ They are usually few in number, but occasionally occur in such large numbers that they cause intestinal obstruction. Unlike the tapeworm no intermediate host is required for the development of this worm. ”

“ Mention is made under Tapeworm of the worms of that species inhabiting the human body as parasites, and it will be convenient here to mention other parasitic varieties. The most common human parasite is the Ascaris lumbricoides or round worm, found chiefly in children and occupying the upper portion of the intestine. ”