‖Het′e‐ro‐ne‐re″is (?), n. [NL. See Hetero-, and Nereis.] (Zoöl.) A free-swimming, dimorphic, sexual form of certain species of Nereis.
☞ In this state the head and its appendages are changed in form, the eyes become very large; more or less of the parapodia are highly modified by the development of finlike lobes, and branchial lamellæ, and their setæ become longer and bladelike.