Head triangular, margins with a pair of horizontal cephalic furrows. Caudal cirrus present. No eyes. Well-developed subepidermal circular muscles especially laterally in the posterior brain and the mouth regions. Dermal glands in the outer one-fourth to one sixth of the zone between the epidermal basement membrane and the outer circular muscle layer. Dermis not separated from the outer longitudinal muscles by a connective tissue layer. A lot of longitudinal muscle fibres between the dermal glands in the anterior region of the foregut. Numerous horizontal, dorsoventral and oblique muscle fibres in the region of the cerebral organs. Dorsoventral muscle fibres present between the lateral intestinal diverticula. Foregut provided with a distinct dorsal longitudinal muscle layer (horizontal muscle plate). Proboscis with two muscle crosses. A ventral vessel at about the level of the brain commissures. One pair of efferent ducts posteriorly in the excretory system. Where the dorsal ganglia separate from the ventral they are 2.5-3 times larger than the latter. Neurochord-like cells present. Apical sensory organs comprise three ciliated pits. Sexes are separate.
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