Rhopalodinidae 
with the mouth and anus at the same end of It, flve 
oral and five anal ambulacra, ten oral tentacles and cal- 
careous plates, ten anal papillfe and plates, and two rowed 
pedicels. They are sometimes called sea-iiourds. 
Rhopalodon (ro-paro-don), M. [XL., < Gr. i>6- 
mi'Aov, a club, 4- orfoi'f (biovr-) = E. tooth.'] A 
genus of fossil dinosaurs from the Permian 
of Russia, based on remains exhibiting club- 
shaped teeth, as II. u:<unjciihoimi. Fischer. 
Rhopalonema (r6"pa-lo-ne'ma), H. [NL., < Gr. 
poTraAov, a club, + i^/wo, a thread.] A notable 
genus of trachymedusans of the family Trurlii/- 
iicmntidx, represented by such species as li. 
velatum of the Mediterranean. Gencnbawr. 
rhotacise, u. i. See rhotacize. 
rhotacism (ro'ta-sizm), w. [= F. rhotaeisme, < 
LL. rhotacismiis, < LGr. * pwantafioi;, < paraKi^etv, 
rhotacize: see rhotacize.] 1. Too frequent use 
of r. 2. Erroneous pronunciation of r; utter- 
ance of r with vibration of the uvula. 
Neither the Spaniards nor Portuguese retain in their 
speech that strong Rhotacism which they denoted by the 
double rr, and which Camden and Fuller notice as pecu- 
liar to the people of Carlton in Leicestershire. 
Southey, The Doctor, ccxxiii. 
3. Conversion of another sound, as s, into r. 
That too many exceptions to the law of rhotacism in 
Latin exist has been felt by many scholars, but no one has 
ventured a theory that would explain them en masse. 
Amur. Jour. PltUol., IX. 49?. 
Also spelled rotaeism. 
rhotacize (ro'ta-slz), v. i.; pret. and pp. rhota- 
cized, ppr. rhotacizing. [< LGr. puradleiv, make 
overmuch or wrong use of r, < pu, rho, the let- 
ter p, r. Cf. iotacism.] 1. To use r too fre- 
quently. 2. To make wrong use of r; pro- 
nounce r with vibration of the uvula instead of 
the tip of the tongue. 3. To convert other 
sounds, as s, into ); substitute r in pronuncia- 
tion. 
Latin, Umbrian, and other rhotacizing dialects. 
The Academy, Feb. 4, 18S3, p. 82. 
Also spelled rJiotacise, rotaeize, rotacise. 
rhubarb (ro'barb), . and a. [Early mod E. 
also rheubarb, reubarbe, rubarbe, rewbarbe; < OF. 
rubarbe, reobarbe, rheubarbe, reitbarbare, F. rhu- 
barbe = Pr. renbarba = Cat. rinbarbarro = Sp. 
ruibarbo = Pg. reubarbo, ritibarbo = It. rcobar- 
baro, rabarbaro, formerly rabbarbaro = D. ra- 
barber = G. rhabarber = Dan. Sw. rabarber 
(Turk, ritbds), (. ML. rheiibarbarum, rhubarba- 
rum, also reubarbarum, for rheum bnrbarnni, < 
Gr. pf/ov fldpfiapov, rhubarb, pfjov, rhubarb (pijov, 
ML. rheum, being appar. a deriv. or orig. an adj. 
form of 'Pd, the Sha, or Volga river, whence 
rhubarb was also called rha Ponticum, 'Pontie 
rha' (see rhapontic), and rha barbari/m, ' barbar- 
ous (i. e. foreign) rha'): see rha, Sheunfi, and 
barbarous.] I. w. 1. The general name for 
plants of the genus Rheum, especially for spe- 
cies affording the drug rhubarb and the culinary 
herb of that name. The specific source of the officinal 
rhubarb is still partially in question ; but it is practically 
5159 
in making tarts, pies, etc., is only of recent date. At- 
tempts to use it as a wine-plant have nut been specially 
successful. Some other species have a similar aeid quality. 
From their stature and huge leaves, various rhubarbs pro- 
duce striking scenic effects, especially It. Einodi, the Ne- 
pal rhubarb, which grows 5 feet high and has wrinkled 
leaves veined with red ; and still more the better-formed 
It. nficinale. A liner and must remarkable species is 
/;. iiMle, the Sikhim rhubarb, which presents a conical 
tower of imbricating foliage ayard or more high, the ample 
shining-green root-leaves passing into large straw-colored 
bracts which conceal beautiful pink stipules and small 
green flowers. The root is very long, winding among the 
rocks. This plant is not easily cultivated. 
2. The root of any medicinal rhubarb, or some 
preparation of it. Rhubarb is a much-prized remedy, 
remarkable as combining a cathartic with an astringent 
etfect, the latter succeeding the former. It is also tonic 
and stomachic. It is administered in substance or in va- 
rious preparations. 
The patient that doth determine to receiue a little Rheu- 
barb sutfereth the bitternesse it leaueth in the throte for 
the profile it doth him against his feuer. 
Guevara, Letters (tr. by Hellowes, 1577), p. 242. 
What r?mbarb, cyme, or what purgative drug, 
Would scour these English hence? 
Shak., Macbeth, v. 3. 55. 
3. The leafstalks of the garden rhubarb col- 
lectively; pie-plant Bog-rhubarb, see Petasttes. 
Compound powder of rhubarb. See powder. False 
rhubarb, Thalictrum llamm. Monk's rhubarb, the 
patience-dock, Rumex Patientia, probably from the use of 
its root like rhubarb ; also, a species of meadow-rue, Tha- 
lictrmn Jtavum. Poor man's rhubarb, Thalictrum fa- 
vitm. 
II. t " Resembling rhubarb ; bitter. 
But with your rubarbe words ye must contend 
To grieue me worse. 
Sir r. Sidney, Astrophel and Stella, xiv. 
rhllbarbativet, " [(. rhubarb +-atiee.] Like 
rhubarb; hence, figuratively, sour. [Rare.] 
A man were better to lye vnder the hands of a Hang- 
man than one of your rhubarbatiuc faces. 
Delcker, Match Me in London, iii. 
rhubarby (ro'biirb-i), . [< rhubarb + -i/ 1 .] 
Like rhubarb; containing,or in some way quali- 
fied by, rhubarb. 
rhumb, mmb (rumb or rum), n. [Formerly 
also rlmme, roomb, roumb, roumbe; prob. < OF. 
rhomb, rumb, rhombe, a point of the compass, 
< Sp. rumbo, a course, point of the compass, = 
Pg. rumbo, rumo, a ship's course (quarto do 
rumo, a point of the compass), = It. rombo, < L. 
rhombus, a magician's circle, a rhombus, < Gr. 
po/i/jof, a spinning-top, a magic wheel, a whirl- 
ing motion, a rhomb in geometry : see rhomb.] 
1. A vertical circle of the celestial sphere. So 
says Button; but if so, it is difficult to understand how 
Kepler (Epitom. Astron., ii. 10), in order to explain def. 2, 
is driven to the trapezoidal figure of the points on the 
compass-card. 
2. A point of the compass, a thirty-second 
part of the circle of the horizon, 11 15' in 
azimuth. 3. The course of a ship constantly 
moving at the same angle to its meridian; a 
rhumb-line. 
rhumb-line (rumb'lln), H. The curve described 
upon the terrestrial spheroid by a ship sailing 
on one course that is, always in the same 
direction relatively to the north point. For long 
courses, especially in high latitudes, the rhumb-line is not 
the shortest or geodetical line, which is substantially a 
great circle ; for the rhumb-line evidently goes round and 
round the pole, approximating to the equiangular spiral. 
Also called loxodromic curve. 
rhumb-sailing (rumb'sa/'ling), . In uariy,, 
the course of a vessel when she keeps on the 
rhumb-line which passes through the place of 
departure and the place of destination. See 
sailing. 
rhumet, See rhumb. 
Rhynchaea 
Rhus (rus), H. [NL. (Tournefort, 1700), < L. rhux, 
< Gr. poi'f, sumac.] A genus of shrubs and trees, 
belonging to the tribe Spondieee of the order 
.liiaranliiiccir, the cashew-nut family. It is char- 
acterized by flowers with from four to ten stamens, a soli- 
tary ovule pendulous from a basilar stalk, a small four- to 
six-cleft calyx, and four to six imbricated petals unchanged 
after flowering. The leaves are pinnate, one- to three-fo- 
liolate, or sometimes simple ; the flowers are small, in axil- 
lary or terminal panicles ; the fruit is a small compressed 
drupe. The plant often abounds in a caustic poisonous 
juice, sometimes exudes a varnish. There are about 120 
species, found throughout subtropical and warm climates, 
but infrequent in the tropics. They are especially abun- 
dant at ttie Cape of Good Hope, also in eastern Asia ; 4 
species are found in southern Europe, a few in the East 
Indies and the Andes, and 13 in the United States. Several 
species, some useful for tanning, are known as sumac. 
(For poisonous American species, see poison-ivy, poison-oak, 
and pouvnwood.) It. Cotinus is the smoke-tree, mist-tree, 
or purple fringe-tree. (See smoke-tree; also younff fustic, 
under J'uslic.) A somewhat similar species, R. colinoides, 
is known as chittam-uood. ft. vernictfera is the Japanese 
lacquer-tree or varnish-tree. (See lacquer-tree.) The kin- 
dred black-varnish tree is of the genus ilelanurrhosa. It. 
succedanea is the Japanese wax-tree. R. semialata bears 
the Chinese galls. R. caustica, the lithy-tree of Chili, 
is a small tree with very hard useful wood. E. integri- 
joliu, though often but a shrub, is said to be the local 
"mahogany" in Lower California. See cut in preceding 
column. 
rhusma (rus'ma), . [Also rumiia; origin un- 
known.] A depilatory composed of lime, or- 
piment, and water, and called in the United 
States Dispensatory "Atkinson's depilatory." 
It is used not only for removing superfluous human hair, 
but also to some extent in tanning and tawing for remov- 
ing hair from skins. 
rhyacolite (ri-ak'o-llt), . [< Gr. pi-af (/wo*-), 
a stream (< pen; flow), + AiBoc, a stone.] A 
name given to the glassy feldspar (orthoclase) 
from Monte Somma in Italy. Also spelled 
tyaeoUte. 
Rhyacophila (ri-a-kof/i-la), H. [NL., < Gr. pia* 
(bvaK-), a stream, + <jn/.elv, love.] The typical 
genus of Ilhyacophilidas. 
Rhyacophilidse (ri"a-ko-fil'i-de), n. pi. [NL., 
< Rhyacophila 4- -idee.] A family of trichopter- 
ous neuropterous insects, typified by the genus 
Rhyacophila. The larvae inhabit fixed stone cases in 
torrents, and the pupae are inclosed in a silken cocoon. 
The forms are numerous, and are mostly European. 
Rhyacophilus (ri-a-kof'i-lus), n. [NL. (Kaup, 
1829), < Gr. praf (/WOK-), a stream, + Qiteiv, 
love.] A genus of Scolopacidse, belonging to the 
totanine section, having a slender bill little 
longer than the head and grooved to beyond the 
middle, legs comparatively short, a moderate 
basal web between the outer and middle toes, 
the plumage dark-colored above with small 
whitish spots, and the tail rounded, fully barred 
with black and white ; the green sandpipers or 
solitary tattlers. The green sandpiper of Europe, S. 
ochropus, is the type. The similar American species is R. 
Medicinal Rhubarb (Rltettm ojficinale). 
settled that R. officinale is one of the probably several spe- 
cies which yield it. It. palmatum, R. Franzfnbacliii, and 11. 
hybridum also have some claims. The article is produced 
on the high table-lands of western China and eastern Ti- 
bet, and formerly reached the western market by the way 
of Russia and Turkey, being named accordingly. It is now 
obtained from China by sea (Chinese rhubarb), but is more 
mixed in quality, from lack of the rigorous Russian in- 
spection. Various species, especially R. Rhaponticum 
and It. palmatH-m, have been grown iu England and else- 
where in Europe for the root, but the product is inferior, 
from difference either of species or of conditions. The 
common garden rhubarb is It. Kliapuntifinn and its varie- 
ties. It is native from the Volga to central Asia, and was 
introduced into England about 1573. Its leaves were 
early used as a pot-herb, but the now eonimun use of its 
tender acidulous leafstalks as a spring substitute for fruit 
Solitary Sandpiper (Rhyacophilits solitariuj 
solitarius, commonly called the solitary sandpiper, abun- 
dant about pools and in wet woods and fields throughout 
the greater part of the United States. It is 8J inches long 
and l(i in extent of wings. 
rhyme, rhymeless, etc. See rimei, etc. 
Rhynchaea (rinK-ke'a), H. [NL. (Cuvier, 1817), 
also Klii/iichea, liijnehxa, liynchea, Rynchcea ; 
prop, fijfcynctama (Gloger, 1849), < LGr. />ty- 
a, with a large snout, < Gr. Myxoti snout, 
Branch of Poison-ivy (Rhtts Toxicottritdron) with Male Flowers. 
<f. inaL- llower; b, fruity. 
