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Online Dictionary of Invertebrate Zoology: Complete Work - Best Text

Online Dictionary of Invertebrate Zoology: Complete Work - Best Text

Online Dictionary of Invertebrate Zoology: Complete Work - Best Text

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192Maggenti and Gardnerchiasma n.; pl. -mata [Gr. chiasma, cross] 1. (ARTHRO: Insecta)A crossing <strong>of</strong> nerves in the nerve center. a. External(outer): a crossover between the lamina ganglionaris andthe medulla externa. b. Internal (inner): a crossover betweenmedula externa and medula internal. 2. An X-shapedchromosome formation seen in meiotic cell division, due tobreakage, exchange, and reciprocal fusion <strong>of</strong> equivalentsegments <strong>of</strong> homologous chromatids. chiasmic a.chiasmatype theory A Genetic theory postulating chiasmataare the result <strong>of</strong> crossing-over; being formed at the rightpoints at which the exchange between (non-sister) chromatidstook place.chiaster n. [Gr. χ; aster, star] (PORIF) A type <strong>of</strong> microsclereaster with very blunt rays.chiastoneury n. [Gr. chiasma, cross; neuron, nerve] (MOLL) Inprosobranchs and a few other taxa, a condition in whichthe visceral loop is distinctively twisted; crossing <strong>of</strong> the visceralconnectives; streptoneury. chiastoneural a. seeorthneury, euthyneury.chilaria n.pl.; sing. chilarium [Gr. cheilos, lip] (ARTHRO: Chelicerata)In Merostomata, small rudimentary appendageson the reduced 7th (pregenital) metamere <strong>of</strong> king crabs.chilidium n. [Gr. dim. cheilos, lip] (BRACHIO) A plate coveringthe notothyrium, when present, in the dorsal valve; chilidialplates if more than one. see homeochilidium.chilognath n. [Gr. cheilos, lip; gnathos, jaw] (ARTHRO: Diplopoda)Fusion <strong>of</strong> the first maxillae into a lower lip or gnathochilarium.Chilopoda, chilopods n.; n.pl. [Gr. cheilos, lip; pous, foot] Agroup <strong>of</strong> terrestrial arthropods, commonly called centipedes,characterized by having numerous trunk segments,each with a single pair <strong>of</strong> walking legs, except the firstsegment that bears a pair <strong>of</strong> forcipulate poison fangs.chiloscleres n. [Gr. cheilos, lip; skleros, tough] (ARTHRO: Insecta)Dark brown spots, on either side <strong>of</strong> the labrum incertain ant larvae.chimera, chimaera n.; pl. -ras [Gr. chimaira, she-goat] Anindividual with a mixture <strong>of</strong> tissues, genetically different in

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