This section may be considered as comprising those Scolecids in which the body has an elongated and cylindrical shape. Strictly speaking, it should include the Nemertida, but the division is not founded upon anatomical characters, and is employed here simply for convenience. Most of the Nematelmia possess an annulated integument; but there is no true segmentation, and there are rarely any locomotive appendages attached to the body. The majority are unisexual, and parasitic during the whole or a part of their existence. Three orders are comprised in this division - viz., the Acanthocephala, the Gordiacea, and the Nematoda.