pairing a. [L. par, equal] Chromosome pairing, highly specific association (side by side) of homologous chromosomes.
pala n.; pl. palae [L. pala, shovel] (ARTHRO: Insecta) In corixid Hemiptera, the tarsus modified as a hair-fringed scoop for particle feeding.
palaeartic region A zoogeographical region encompassing Europe and northern Asia including Japan, the Middle and Near East and areas along the southern coast of the Mediterranean Sea.
palatal a. [L. palatum, palate] 1. Belonging to the outer lip. 2. (MOLL: Gastropoda) Referring to folds and lamellae of the shell.
palatal setae (ARTHRO: Insecta) In Culicidae, four small peglike cibarial setae located on the anterior hard palate.
palate n. [L. palatum, roof of the mouth] 1. (ARTHRO: Diplo-poda) The endostome. 2. (ARTHRO: Insecta) The epiphar-ynx. 3. (BRYO: Gymnolaemata) In Cheilostomata, the mandibular part of the avicularium.
palatum n. [L. palatum, roof of the mouth] (ARTHRO: Insecta) In Culicidae, the oral surfaces of the labrum and clypeus; divided into labropalatum and clypeopalatum.
palea n.; pl. paleae [L. palea, chaff] (ANN: Polychaeta) A broad flattened seta used for burrowing.
paleospecies n. [Gr. palaios, ancient; L. species, form] Fossils that are placed in a species because of similar appearance.
paleotropical n. [Gr. palaios, ancient; tropos, turn] Of or pertaining to the tropical or subtropical regions of the old world.
palette n. [L. pala, spade] (ARTHRO: Insecta) In males of Coleoptera, the modified cupule-bearing tarsus of an anterior leg.
pali n.pl.; sing. palus [L. palus, stake] 1. (ARTHRO: Insecta) A straight or pointed spine. 2. (CNID: Anthozoa) Small ridges between the columella and septa of scleractinian corals.
palidium n.; pl. -ia [L. dim palus, stake] (ARTHRO: Insecta) In scarabaeoid larvae, a paired group of spines placed either before the anus or from the ends of the anal slit; the pali are recumbent and may occur in one to many rows.
paliform lobe (CNID) A palus detached from the inner edge of a septum.
palingenesis n. [Gr. palin, back; genesis, descent] 1. Characteristics of an individual that repeats the phylogenetic de velopment of its taxon. 2. The regeneration or restoration of a lost part. 3. Abrupt metamorphosis. see cenogenesis, recapitulation theory.
palintrope n. [Gr. palin, back; tropos, turn] (BRACHIO) The recurved part of the ventral valve that fills the gap between the beak and hinge line in the dorsal valve of some shells.
palisade n. [L. palus, stake] (ARTHRO: Insecta) The clear region formed around the rhabdom in a light-adapted eucone apposition eye when exposed to darkness.
pallets n.pl. [L. dim. pala, spade] (MOLL: Bivalvia) Two variously shaped calcareous structures at the siphonal tip of some woodboring forms; abrading tools.
pallial a. [L. pallium, mantle] (MOLL) Of or pertaining to the mantle.
pallial artery (MOLL) An artery that supplies blood to the mantle.
pallial chamber or cavity (MOLL) The mantle cavity.
pallial complex (MOLL) All of the organs of the mantle cavity combined (ctenidia, osphradia, anus, renal and genital openings and glands).
pallial curtain (MOLL: Bivalvia) The inner fold of the mantle edge of oysters, with a row of tentacles, supplied with muscles and blood sinuses.
pallial duct (MOLL: Gastropoda) Region of the genital duct that has undergone elaboration or differentiation to provide for sperm storage and egg membrane formation.
pallial groove (MOLL: Polyplacophora) Ventral groove marking the separation between the foot and mantle.
pallial line (MOLL: Bivalvia) A fine, single-lined impression near the periphery of each valve, produced by the edge of the mantle and indicating the internal line of attachment of the mantle to the shell.
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