head-fans (ARTHRO: Insecta) In Diptera, fan-like rays on the main part of the torma of mature larva of Simuliidae that function as filtering organs in running water, or a raking function in Crozetia .
head gland (PLATY: Trematoda) Glands of circaria which produce a secretion emitted into the matrix of the tegument that is thought to function in the postpenetration adjustment of the schistosomula.
head valve (MOLL: Polyplacophora) The anterior valve of chitons.
heart n. [A.S. heorte] Sometimes used to describe the pulsating dorsal blood vessel.
heart chamber (ARTHRO: Insecta) One of the segmental swellings of the dorsal blood vessel; ventricle.
heautotype n. [Gr. heautou, of itself; typos, image] A specimen used by the original describer as an illustration of his species and compared with the type or cotype; a hypotype.
hectocotylus, heterocotylus n. [Gr. hekaton, hundred; ko-tyle, a cup] (MOLL: Cephalopoda) A penislike process or arm utilized in spermatophore transfer to the mantle cavity of the female, in some species breaking off in the process.
heel n. [A.S. hela, heel] (ARTHRO: Insecta) In Hymenoptera larvae, padlike prolongation of the base of the tarsungulus opposing the claw.
height n. [A.S. hiehthu, height] 1. (MOLL: Gastropoda) The length parallel to the shell axis through the columella. 2. (MOLL: Bivalvia) The greatest vertical dimension through the beak at right angles to a line bisecting the adductor scars; altitude.
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