Part 324

Rhab"do*lith (?), n. [Gr. "ra`bdos a rod + -lith.] A minute calcareous rodlike structure found both at the surface and the bottom of the ocean; -- supposed by some to be a calcareous alga.

Rhab*dol"o*gy (?), n. Same as Rabdology.

Rhab"dom (rb"dm), n. [Gr. "ra`bdwma a bundle of rods, fr. "ra`bdos a rod.] (Zoöl.) One of numerous minute rodlike structures formed of two or more cells situated behind the retinulæ in the compound eyes of insects, etc. See Illust. under Ommatidium.

Rhab"do*man`cy (?), n. Same as Rabdomancy.

Rhab"do*mere (?), n. [Rhabdom + -mere.] (Zoöl.) One of the several parts composing a rhabdom.

||Rhab*doph"o*ra (?), n. pl. [NL., fr. Gr. "ra`bdos a rod + &?;&?;&?; ||to bear.] (Zoöl.) An extinct division of Hydrozoa which includes the ||graptolities.

||Rhab`do*pleu"ra (?), n. [NL., fr. Gr. "ra`bdos a rod + &?;&?;&?;&?; ||the side.] (Zoöl.) A genus of marine Bryozoa in which the tubular ||cells have a centralchitinous axis and the tentacles are borne on a ||bilobed lophophore. It is the type of the order Pterobranchia, or ||Podostomata

Rhab"do*sphere (?), n. [Gr. "ra`bdos a rod + E. sphere.] A minute sphere composed of rhabdoliths.

||Rha`chi*al"gi*a (?), n. [NL.] See Rachialgia.

Rha*chid"i*an (?), a. Of or pertaining to the rhachis; as, the rhachidian teeth of a mollusk.

||Rhach`i*glos"sa (?), n. pl. [NL. See Rhachis, and Glossa.] (Zoöl.) A ||division of marine gastropods having a retractile proboscis and three ||longitudinal rows of teeth on the radula. It includes many of the ||large ornamental shells, as the miters, murices, olives, purpuras, ||volutes, and whelks. See Illust. in Append.

||Rha*chil"la (?), n. [NL., fr. Gr. "ra`chis the spine.] (Bot.) A ||branch of inflorescence; the zigzag axis on which the florets are ||arranged in the spikelets of grasses.

Rha"chi*o*dont (?), a. [Gr. "ra`chis, -ios, the spine + &?;&?;&?;, &?;&?;&?;, a tooth.] (Zoöl.) Having gular teeth formed by a peculiar modification of the inferior spines of some of the vertebræ, as certain South African snakes (Dasypeltis) which swallow birds' eggs and use these gular teeth to crush them.

||Rha"chis (?), n.; pl. E. Rhachises (#), L. Rhachides (#). [See ||Rachis.] [Written also rechis.] 1. (Anat.) The spine.

2. (Bot.) (a) The continued stem or midrib of a pinnately compound leaf, as in a rose leaf or a fern. (b) The principal axis in a raceme, spike, panicle, or corymb.

3. (Zoöl.) (a) The shaft of a feather. The rhachis of the after-shaft, or plumule, is called the hyporhachis. (b) The central cord in the stem of a crinoid. (c) The median part of the radula of a mollusk. (d) A central cord of the ovary of nematodes.

||Rha*chi"tis (?), n. [NL.] See Rachitis.

Rhad`a*man"thine (?), a. Of or pertaining to Rhadamanthus; rigorously just; as, a Rhadamanthine judgment.

Rhad`a*man"thus (?), n. [L., fr. Gr. &?;&?;&?;.] (Greek Mythol.) One of the three judges of the infernal regions; figuratively, a strictly just judge.

Rhæ"ti*an (?), a & n. Rhetain.

Rhæ"tic (?), a. [L. Rhaeticus Rhetian.] (Geol.) Pertaining to, or of the same horizon as, certain Mesozoic strata of the Rhetian Alps. These strata are regarded as closing the Triassic period. See the Chart of Geology.

Rhæ"ti*zite (?), n. [So called from L. Rhaetia, Raetia, the Rhetian Alps, where it is found.] (Min.) A variety of the mineral cyanite.

||Rham`a*dan" (?), n. See Ramadan.

Rham*na"ceous (?), a. (Bot.) Of or pertaining to a natural order of shrubs and trees (Rhamnaceæ, or Rhamneæ) of which the buckthorn (Rhamnus) is the type. It includes also the New Jersey tea, the supple-jack, and one of the plants called lotus (Zizyphus).

||Rham"nus (?), n. [NL., from Gr. "ra`mnos a kind of prickly shrub; cf. ||L. rhamnos.] (Bot.) A genus of shrubs and small trees; buckthorn. The ||California Rhamnus Purshianus and the European R. catharticus are ||used in medicine. The latter is used for hedges.

||Rham`pho*rhyn"chus (?), n. [NL., fr. Gr. "ra`mfos a beak + ||&?;&?;&?;&?; snout.] (Paleon.) A genus of pterodactyls in which the ||elongated tail supported a leathery expansion at the tip.

||Rham`pho*the"ca (?), n.; pl. Rhamphothecæ (#). [NL., fr. Gr "ra`mnos ||a beak + &?;&?; a case.] (Zoöl.) The horny covering of the bill of ||birds.

Rha"phe (?), n. [NL., fr. Gr. &?;&?;&?; seam, fr. &?;&?;&?; to sew. ] (Bot.) The continuation of the seed stalk along the side of an anatropous ovule or seed, forming a ridge or seam. [Written also raphe.] Gray.