acron
From ZooTerms (Dictionary of Invertebrate Zoology)
acron (noun; Greek akros, tip): 1. (Arthropoda) The anterior unsegmented, or indistinguishably fused, body segments. a In Crustacea, ophthalmic somite; presegmental region. b.In Insecta, the prostomium.
2. (Mollusca) The prostomal region of trochophore larva.
