A sensory organ, whose functions are not fully understood, consisting of a complex of nervous and glandular tissues surrounding a ciliated canal; in heteronemerteans the organs are closely attached to the posterior margins of the dorsal cerebral lobes, in other groups they form discrete structures, sometimes positioned some distance in front of the cerebral ganglia but linked to them by nerves; cerebral sensory organs are missing from some palaeonemerteans, many polystiliferous hoplonemerteans and the genus Carcinonemertes and the genus Malacobdella .

Alternative forms for cerebral sensory organ : cerebral sense organ, cerebral sense organs, cerebral sensory organs.