(Possibly Kinorhyncha (q.v.) with only Echinoderes is to be placed here).
KINORHYNCHA, an isolated group of minute animals containing the single genus Echinoderes F.
The Kinorhyncha are dioecious.
The thick-skinned round worms, such as the common horse-worm and the threadworms (see Nematoda), together with the Nematomorpha, Chaetosomatida, Desmoscolecida and Acanthocephala, form a fairly natural group. The Rotifera, with probably the Kinorhyncha and Gastrotricha, are again isolated.