Diactine see diactinal monaxon

diaene n. [Gr. dis, twice; triaina, trident] (PORIF) A form of tri-aene produced by loss of one ray from the cladome.

diaeresis n. [Gr. diairein, to divide] (ARTHRO: Crustacea) A transverse groove on the posterior part of an exopod (rarely endopod) of a uropod appendage; occasionally dividing the exopod into two movable parts.

diagenodont teeth (MOLL: Bivalvia) Having differentiated cardinal teeth (up to 3) and lateral teeth (up to 2) on the hinge plate.

diagnosis n.; pl. -noses [Gr. diagignoskein, to distinguish] A formal statement of the characters distinguishing one taxon from closely related taxa.

diagnostic a. [Gr. diagignoskein, to distinguish] Uniquely characterizing a taxon.

diagonal ridge (MOLL: Bivalvia) A ridge running diagonally from the umbo toward the posteriolateral margin of the valve.

diakinesis n. [Gr. dia, through; kinesis, movement] The final stage of prophase in the first meiotic division; paired, contracted chromosomes with the disappearance of nucleolus and nuclear envelope.

dialyneury n. [Gr. dialyein, to reconcile; neuron, nerve] (MOLL: Gastropoda) Having zygoneural connections on both left and right sides.

dialysis n.; pl. dialyses [Gr. dia, through; lyein, to loose] Separation of dissolved crystalloids and colloids through a suitable membrane.

dialyzate, dialysate n. [Gr. dia, through; lyein, to loose] Used for both the material that will and will not diffuse through a membrane.

diamorph n. [Gr. dia, through; morphe, form] (PORIF) A cell mass of spherical form and a continuous pinacoderm formed as a result of aggregation of dissociated cells.

diapause n. [Gr. dia, through; pausis, a stopping] A quiescent phase during the development of an organism in which most physiological processes are suspended; maybe optional, obligatory or internally controlled. see amphody-namous.

diaphanous a. [Gr. dia, through; phanos, light] Showing light through its substance; transparent; translucent; clear.

diaphragm n. [Gr. diaphragma, partition, wall] 1. Any of the horizontal dividing membranes of a body cavity. 2. A structure controlling admission of light through an aperture. 3. (ARTHRO: Insecta) a. In Heteroptera, separating the general body cavity from the genital chamber. b. In Lepidoptera, that which closes the body cavity caudally, comprised of dorsally the fultura superior and ventrally the fultura inferior. 4. (BRYO) a. In Stenolaemata, the membranous or skeletal partition which extends transversly across the entire zooidal chamber. b. In Gymnolaemata autozooids, the muscular ring of the body wall. 5. (CNID: Hydrozoa) A delicate chitinous floor that supports the hy-dranth. 6. (ECHI) A thin-walled, funnel-like septum incompletely separating an anterior or peripharyngeal coelom from the general body cavity.

diapolar cells (MESO) Ciliated somatodermal cells located between the parapolar and uropolar cells; trunk cells.

diarhyses n.pl. [Gr. dis, twice; rhysus, delivering] (PORIF: Hexactinellida) Radial canals that run through the skeletal wall and have a single flagellated chamber.

diarthrosis n. [Gr. dis, twice; arthron, joint] An articulation that permits free movement. diarthrodial a.

diarticular a. [Gr. dis, twice; articulus, joint] Said of, or pertaining to two joints.

diastase, diastatic see amylase diastole n. [Gr. diastole, difference] The regular expansion of the heart during which it fills with blood; the relaxatory phase. diastolic a. see systole.

diastomian a. [Gr. dia, through; stoma, mouth] (ARTHRO: In-secta) Pertaining to the orifice, (excluding ostiole), of the metathoracic scent gland of Heteroptera, consisting of a pair of relatively widely spaced openings. see omphalian.

diastomatic a. [Gr. dia, through; stoma, mouth] Through the stomata or pores.

diathesis n. [Gr. dia, through; thesis, position] An inherited constitutional state whereby an individual is especially vulnerable to a certain type of reaction, disease or development.

diatom rake (ARTHRO: Insecta) A structure of the galea of mayfly nymphs composed of bristles and pectinated spines, or of hairs or spines on the maxillae, functioning in scraping food.

diaulic a. [Gr. dis, twice; aulos, pipe] 1. With two separate ducts open to the surface. 2. (MOLL: Gastropoda) Male and female portions with separate gonopores. see monaulic, triaulic.

di-axial (ARTHRO: Chelicerata) Pertaining to chelicerae of spiders with the paturon projecting either forward or down with the fangs moving inward towards each other. see par-axial.

diaxon n. [Gr. dis, twice; axon, axis] Having two axes or two axis-cylinder processes.

diblastula n. [Gr. dis, twice; blastos, bud] (CNID) A coelenter-ate embryo consisting of 2 layers arranged around a central cavity.

dibranchiate a. [Gr. dis, twice; branchia, gills] Having two gills.

dicentric a. [Gr. dis, twice; kentron, midpoint of a circle] Having chromosomes or chromatids with two centromeres.

dicerous, dicerus a. [Gr. dis, twice; keros, horn] Having two horns, tentacles or antennae.

dichogamy n. [Gr. dicha, in two; gamos, marriage] The production of male and female gametes at different times in an hermaphroditic organism; protogynous and protandrous hermaphrodites. dichogamous a. see homogamy.

dichopatry n. [Gr. dicha, in two; L. patria, native country] Populations geographically separated to the extent that individuals of the involved species never meet. see parapa-tric speciation.

dichoptic a. [Gr. dicha, in two; ops, sight] Having eyes separated dorsally by integument. see holoptic.

dichotomize v.t. & i. [Gr. dicha, in two; temnein, to cut] To cut into two parts; to divide into pairs.

dichotomous a. [Gr. dicha, in two; temnein, to cut] Divided or dividing into two parts; successive bifurcation; two-forked. dichotomy n.

dichotriaene n. [Gr. dicha, in two; triaina, trident] (PORIF) A tetractinal megasclere with forked clads.

dichroism n. [Gr. dis, twice; chros, color] The property of showing two very different colors, one by transmitted light and the other by reflected light, or as some dyes staining different tissues different colors.

dichromatic a. [Gr. dis, twice; chroma, color] 1. Having two color varieties. 2. Seeing only two colors.

dichthadiform ergatogyne (ARTHRO: Insecta) In army ants, an individual of an aberrant reproductive caste, characterized by a wingless alitrunk, large gaster, and expanded postpetiole.

dichthadiigyne n. [Gr. dichthadios, double; gyne, female] (ARTHRO: Insecta) A permanently wingless ant with greatly reduced eyes, massive pedicel, abdomen and ovaries, and strong legs.

dicondylic a. [Gr. dis, twice; kondylos, knuckle] Pertaining to an articulation with two condyles; bicondylar.

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