<P> In the 13th century, worms were recognized in Europe as part of the category of reptiles that consisted of a miscellany of egg - laying creatures, including "snakes, various fantastic monsters, lizards, assorted amphibians," as recorded by Vincent of Beauvais in his Mirror of Nature . In everyday language, the term worm is also applied to various other living forms such as larvae, insects, millipedes, centipedes, shipworms (teredo worms), or even some vertebrates (creatures with a backbone) such as blindworms and caecilians . Worms can be divided into several groups, but are still technically decomposers . </P> <Ul> <Li> The first of these, Platyhelminthes, includes the flatworms, tapeworms, and flukes . They have a flat, ribbon - or leaf - shaped body with a pair of eyes at the front . Some are parasites . </Li> <Li> The second group contains the threadworms, roundworms, and hookworms . This phylum is called Nematoda . Threadworms may be microscopic, such as the vinegar eelworm, or more than 1 metre (3 feet) long . They are found in damp earth, moss, decaying substances, fresh water, or salt water . Some roundworms are also parasites . The Guinea worm, for example, gets under the skin of the feet and legs of people living in tropical countries . </Li> <Li> The third group consists of the segmented worms, with bodies divided into segments, or rings . This phylum is called Annelida . Among these are the earthworms and the bristle worms of the sea . </Li> </Ul> <Li> The first of these, Platyhelminthes, includes the flatworms, tapeworms, and flukes . They have a flat, ribbon - or leaf - shaped body with a pair of eyes at the front . Some are parasites . </Li> <Li> The second group contains the threadworms, roundworms, and hookworms . This phylum is called Nematoda . Threadworms may be microscopic, such as the vinegar eelworm, or more than 1 metre (3 feet) long . They are found in damp earth, moss, decaying substances, fresh water, or salt water . Some roundworms are also parasites . The Guinea worm, for example, gets under the skin of the feet and legs of people living in tropical countries . </Li>

Which of the following is a source of parasitic worms