New sense organ in larval hookworms.

A new ciliary sense organ is described which is bilaterally arranged, one in each lateral cord. It is just posterior to the nerve ring and adjacent to the excretory duct. The cilium is closely associated with another structure which is itself connected to the cuticle beneath the lateral alae. A nervous circuit is proposed which links this receptor via the hemizonid to the nerve ring. The receptor and associated structures are in the infective larvae of Necator americanus and Ancylostoma tubaeforme.