RHU
but the flufl of ils back is divided by lines, fomething in the manner of the lkins of fnakes. The mouth is very large, and is well furniftied with teeth ; and the palate has a number of tubercles, armed alfo with a fort of teeth. It feeds on fifli, and its flefli is very delicate. It is very common in the mar- kets at Venice, and'isc3ught in the neighbouring leas, and in many other places. Wwvghkf* Hift. Fife. p. 92. Gef- ner 9 p. 778. Aldrov. de Pile. 1. 2. c. 48. ^HOMBOID/EUS major and minor, names given by Albinus to what he makes two mufcles ; though Winflow and others account it only one. What Winflow calls the inferior por- tion of the rhomboidalis, Albinus calls rhomboidesus major, and what he calls the upper portion of that mufcle, Albinus calls rhomboideem minor. Sec the article Scapula.
RHOMBOIDALIS. See the articles Rhomboidjeus and Scapula.
RHOMBOIDES, in anatomy, a mufcle, which is a thin, broad, and oblique fquare flemy plane, fituated between the bafis of the fcapula and the fpina dorfi. It may be divided into two portions, one fuperior, the other inferior, which fometimes appear feparate. The fuperior portion, which feems in fome fubjecls to be made up of two, is fixed by an infertion wholly flemy in the two or three loweft fpinal apophyfes of the neck, and partly in the pofterior cervical ligament. The inferior portion is fixed by a tendinous plane in the three or four uppermoft fpinal apophyfes of the back.
Thefe two portions, of which the inferior is much the broad- eft, being united, are inferted in the edge of the bafis fca- pulse, from the finall triangular fpace to the inferior angle, the fuperior portion covering a {mall portion of the angu- laris at its infertion. This whole mufcle is covered by the trapezius, and covers the ferratus pofticus fuperior, being joined to each of thefe mufcles by a filamentary or cellular . fubftance. f&tnftow's Anatoi&y, p. 174.
RHOMBOIDIA, in natural hiitory, the name of a genus of fpars, given them from their being of a rhomboidal form. They owe this figure to an admixture of particles of iron, and confifts of fix planes.
'Of this genus there are only two known fpecies. 1, A white thin one with very thin crufts ; and 2. A whitifh brown thick one with thicker crufts. Thefe are both found in the foreft of Dean in Gloucefterfhire, and in other places where there are iron ores.
RHOMBUS (Cycl.) — Solid rhombus, in geometry, two equal and right cones joined together at their bafes.
Rhombus, in zoology, a genus of fifties, which are ovipa- rous, and have a flat, ihort, and fomewhat fquared body, and fwim on one fide. The turbot and other fiffi of that make, are of this genus. The fides of thefe fifh are equal, but their angles unequal. l¥illughby\ Hift. Pifc. p. 93.
Rhombus, in conchyliology, the name given by the generality of authors to a genus of the fhell fifh, much more properly called by fome cyltndrus. See Cylindrus.
RHOPALOSIS, a diftemper of the hair defcribed by the an- tients, and feeming to be the fame with what we call the plica polon'tca, being a fort of matting together of the hair into long and thick trefles.
RHOPE, a word ufed by the Greek writers, to exprefs a vio- lent tendency of the humors to any particular part of the Ijody.
RHOX, a word ufed by fome authors to exprefs the tunica uvea
' of the eye.
RHUBARB (Cycl.) — The Indian rhubarb fowu in our gardens has this peculiar property, that it yields a fine and clear gum. This is perfectly white and pellucid, and in the months of June and July is fo plentiful, that an ounce may fometimes be gathered at a time from one plant of it. It exfudates of jtfelf from all parts of the ftalks and ribs of the leaves, and fometimes from the under part of the leaves themfelves. It Hands in fome places in large drops, and in others the ftalks, &c. feem only to be covered with a thin layer of it ; and the under part of the leaves in fome have it in form of twifted wires or long icicles. The plant may always be ken wounded by a fort of cauftic in the places where the germen makes its way out, and thefe may be followed with any pointed inftrument through the fkin ; in fome parts of the plant this juice is found to be turned gummy within it, and looks like clear ice. As this is the only known herbaceous plant, that yields a true gum like that of trees, it would be worthy obfervation, whether or not fome of our own plants have fome tendency of nature, to form a juice of the fame kind. It would be moft proper to look for this in the plants of the fame genus, and as nearly related to the rhu- barb as we can. The docks fo common about our fields .are of the fame genus ; and the Ibrre] fhews, by its tafte that it is particularly allied to the plant ; for both are alike oi' the dock kind, and both alike four. It would be proper to look carefully about the leaves of forrel a little before it flowers, to 'fee whether any thing like the fame gum appears • on it.
There is yet this farther analogy between this rhubarb and our common forrel ; that the hulks of our forrel, boiled in water, with a little alum, turn it to a fine red colour ; and
R I B
the hulks of rhubarb do the fame, and both the one and' the other often turn red in decaying.
The juice of the roots of this rhubarb, extracted by bruifmg and fteeping it in common water, when the liquor if (trained and evaporated, becomes only a clear uninflammable gum, and melts in the flame of a candle. This gum, as well as that of the ftalks and leaves,. is of an infipid tafte ; and it is obfervable, that though the plant naturally yields it in fo large a quantity, yet it will not flow from wounds made by art in any part of the plant. Upon the confidera- tion of the infipid tafte cf this gum, and its folubility in water, we may find fome probable conjecture, in regard to the different virtues of this- plant in purging and binding. The woody fibres have a ftrong tafte ; and, in all proba- bility, are alone endued with the aftringent quality. An in- fufion of rhubarb is known to purge, and a powder of it to bind : the reafon is eafily feen on this confidcration. The water in the infufion takes up all this gummy juice, and its other juices, but leaves the fibrofe part behind, in confe- quence of which it ought to purge without binding ; but in cafe of giving the powder, the juices are in great part eva- porated in the drying, and the woody part left almoft alone ; it therefore purges but little, and proves powerfully aftrin- gent. Phil. Tranf. N° 224.
RHUS, fumach, in botany, the name of a genus of trees, the characters of which are thefe. The flower is of the rofaceous kind, and is compofed of feveral petals, difpofed in a circu- lar form. The piftil arifes from the cup, and finally be- comes a roundifh fruit, with a depreffion on one fide, which gives it fomewhat of a kidney like fhape, and containing a feed of the fame figure.
The fpecies of fumach enumerated by Mr. Tourneforf are thefe. J. The common or elm leaved fumach. 2. The Virginian fumach, and 3. The Canada fumach with long leaves fmooth on both fides. Town. Inft. p. 611.
RHUSELINUM, in botany, a name given by fome authors to the ranunculus. Gcr. Emac. Ind. 2.
RHYNE, in botany, a name ufed by fome authors for the camphor tree. Breyn. Prod. VI. p. 4.
RHYTIDOSIS, the name of a diftemper of the eye in which it waftes and wrinkles up.
RHITHM. See the article Rythm.
RIB. See Ribs, infra.
RIBATTUTA, in the Italian mufic, a ftriking or founding the fame note over again. Hence,
Ribattuta dt gola, one of the graces in finging, is per- formed by repeated beating or ftriking a note, from that which is immediately above it. See example A. It differs from a fhake.
E
^Slfert^iS^^
tw*
Ribattuta di gola doppia. See example B. This is pretty near what the French call tour de gojier, or double cadence. Brofard. Di£. Muf.
RIBESIA nigra, black currants, have been long famous In England for quinfies and fore throats, fo as to obtain the name of fquinancy or quinfy berries. See Grossul aria.
rIBS (Cycl.) — The number of thefe varies in different fub- jefls, fometimes in one fide only, and fometimes in both. Anatomifts have divided each rib into the middle part or body, two extremities, the one anterior, the other pofterior ; two fides one external and convex, the other internal and concave ; two edges, one fuperior and the other inferior ; and two labia in each edge, one external, the other inter- nal. The pofterior extremity, which may be called the head of the rib, is articulated with the vertebra? of the back. At the anterior extremity frefb ribs are lengthened out by car- tilaginous epiphyfes, fhick into their bony ends. Each of the true ribs, at the pofterior extremity, has two fmall car- tilaginous imprcflions, diftinguifhed by a kind of angle, by which they are articulated with the lateral cartilaginous im- preffions in the bodies of two vertebra? of the back ; but the firft rib has no more than one fuch imprefiion, being arti- culated with one vertebra only. At a fmall diftance from the head of this extremity pofteriorly is another cartilagi- nous impreflion on each fide, a little convex, and clofely joined to a fmall tuberofity. By thefe the ribs are articu- lated with the lateral cartilaginous impreffions in the tranf- verfe apophyfes of the dorfal vertebra ; and the tuberofities fervefor the infertion of the ligaments; the portion which lies between the head and thefe impremons is contracted, and represents a neck. When the pofterior extremity of a rib is articulated with two vertebrae, the fecond articulation is always with the tranfverfe procefs of the loweft two. Be- tween the tuberofity and middle part of the ribs, there is on their outfide a kind of oblique rough angle of different breadths. In the firft rib, this angle is not diftindt from the
tube-
