rhinophore

from The Century Dictionary.

• noun In Mollusca, one of the hinder pair of tentacles of opisthobranchiate gastropods, supposed to function as olfactory organs; in general, an organ bearing an olfactory sense. Also spelled rhinophor.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Zoöl.) One of the two tentacle-like organs on the back of the head or neck of a nudibranch or tectibranch mollusk. They are usually retractile, and often transversely furrowed or plicate, and are regarded as olfactory organs. Called also dorsal tentacles. See Illust. under pygobranchia, and opisthobranchia.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A club-shaped structure that occurs in pairs as the most prominent part of the external head anatomy of the dorid nudibranchs.