The short, slender tentacles containing the selyn transport nerves.

Lateral tentacles usually lay sheathed along each side of a Sime's forearms.  They are not as long as the handling tentacles, and contain less muscle, and are encased in more tender skin.  They extend for the transference of Selyn during the Kill, for junct, or Transfer for non-juncts.

The lateral tentacles are the organs through which a Sime draws selyn from the Gen. All four laterals must be in contact with the Gen's skin in symmetric pairs -usually on the Gen's arms and a fifth contact point must be made, usually with the lips.  Other contact positions are possible, but less efficient.  See Channel's Destiny. 

'Death by injury to the lateral tentacles, the organs richest in selyn transport nerves, was the second most horrible death a Sime could know. Apparently, it was so horrible that even the Gens who lived with Simes, understood some measure of Klyd's revulsion.' (From House of Zeor  Ch 3)

(Source:  Index card file.  Operation High Time --  Lateral tentacles used only in transfer, but having freedom and sunshine.  Moist, gray-pink color.  All 4 needed to complete transfer --- all 4 must be in skin contact.