R I V 



R 1 X 



of Italy, in the department of the Adda ; 2 miles S. of 

 Crema. 



Rivolta Secca, a town of Italy, in the department of 

 the Adda ; 10 miles W. of Crema. 



RIVOLTARE, Ital. in Mvfic, to reverie ; whence 



RIVOLTATO, reverfed. See Roveisscio. 



RIVOLTELLA, in Geography, a town of Italy; 17 

 miles E. of Brefcia. 



RIUT, a Rufiian fettlement on the W. coaft of Ame- 

 rica. N. lat. 65 25'. E. long. 209° 36'. 



RIVULARIA, in Botany, fo called by Dr. Roth from 

 its growing generally in rivulets, is a cryptogamic genus, 

 feparated, by that able botanift, from Ulva and Conferva; 

 to each of which genera fome or other of its fpecies had 

 been, by preceding writers, referred. — Roth Catal. v. 1. 

 212. Sims and Konig's Ann. of Bot. v. 1. 247. Smith 

 Engl. Bot. v. 25. 1797. — Clafs and order, Cryptogamia 

 Alga. Nat. Ord. .Alg<z fubmerfx. 



Eft. Ch. Frond gelatinous, firm, deftitute of an external 

 cuticle. Fructification among jointed filaments, lodged in 

 the fubftance of the frond. 



Roth defcribes eleven fpecies of this genus, in his Bey- 

 trage, v. I. 239, tranflatrd in Ann. of Bot. above cited. 

 He tlier£ alfo adopts a genus from Micheli, by the name of 

 Linchia, whafe character is as follows. Frond gelatinous, 

 pellucid, enclofed in a membranous pellucid integument, 

 and fluffed with granules of fructification, difpofed in curved 

 beaded lines. Of this he defin.es four fpecies. 



Of his Rivularia; e/egans, 11.5, Engl. Bot. t. 1797, and 

 tuberculofa, n. ii, Engl. Bot. t. 2366, are acknowledged 

 natives of Britain ; as are two of his Linciia ; prumformis, 

 n. 2, which is I) ha prumformis of Linnaeus, and of Engl. 

 Bot. t. 968 ; and Nofloc, n. 3, which is Tremella Nofloc of 

 Linnaeus, and of Engl. Bot. t. 461. The prumformis juft 

 'toned, is in the index to Engl. Bot. referred to Rivu- 

 laria ; how juilly we dare not pofitively fay. In the fame 

 work the following fpecies arc added to thofe of Roth. 

 Refpedling- the marine ones, there may poflibly be fome dif- 

 ference of opinion as to their genus ; but they can fcarcely 

 be referred to any other at prelent eftablilhed. 



R. Opuntia. Indian-fig Rivularia. Engl. Bot. t. 1868. 

 (Fucus Opuntia ; Gooden. and Woodw. Tr. of Linn. Soc. 

 v. 3. 219. Tremella marina ctefpitofa, fegmentis tenuibus ; 

 Dill. Mufc. 50. t. 10. f. 9.) — Comprefled, branched, red, 

 jointed ; joints elliptical, confluent. Internal filaments re- 

 peatedly forked ; their ultimate joints Ihortened, tilled with 

 In da. — Found on rocks, on the Britifii coaft, forming fmall, 

 creeping, purplifh tufts, between high and low-water marks. 

 The fronds are entangled, much branched, eomprefled, of a 

 fpongy texture, but not hollow, compofed of elliptical 

 joints. Thefe, when cut tranfverfely, prove full of innu- 

 merable forked, beaded filaments, whofe joints, near the fur- 

 face of the frond, are fhortelt, and full of red grains, pre- 

 fumed to he feeds. We do not pretend that this fpecies 

 anfwers well to the character of a Rivularia- It will pro- 

 bably hereafter conftitute a new genus, along with feveral 



more, now difperled in Fucus, Conferva or Ulva, but whofe 

 fructification and economy are not fufficiently known, for 

 any decifive im .lime to be taken concerning them. Among 

 them perhaps is Funs Wigghii, Engl. Bot. t. 1 i6c ; for we 

 are not vet perfuadi d of its being a real Rivularia ; nor 

 have 1 ■ . 1 1 . 1 minutely ourfelves. 



R. vermind.it, 1. Worm-lhaped Rivularia. Engl. Bot. 



t. I Rl 8 Cylindrical, much branched, l)rown ; branches 



fcattered, fubdivided, crooked. Internal filaments com- 

 pound and divaricated ; their ultimate branches cindered, 

 beaded, thickened upwards. Fruit obovate, iefiile at the 

 Vol. XXX. 



bafe of the beaded branches. — Found on the coaiU 01 In 

 land and the fouth of England, in fummer. A very curious 

 fubmarine plant, four or live inches high, olive brown, much 

 and irregularly branched, folid, gelatinous, invefled with a 

 pale flimy mafs, of minute, jointed, branched fibres, fome 

 of which are darker, and beaded, and accompanied by a 

 dark, oval, folitary y<W at th ir bafe. 



R. vertici/lala. Whorled Pink Rivularia. Engl. Bot. 

 t. 2466. (Ulva verticillata; With. v. 4. 127. )— Cylindri- 

 cal, much branched, very gelatinous, pale pink ; branches 

 alternate ; the ultimate ones very numerous, of equal thick- 

 nefs. Internal filaments whorled, repeatedly forked. Fruit 

 obovate, lateral. — Found on the fea beach of Ireland and 

 SufTex, in fummer. Highly gelatinous and tender, of a 

 delicate fiefh-colour. Its generic chara&ers nearly accord 

 with the lait. 



R. incraffaia. Thick Green Rivularia. (Ulva incralYata ; 

 Hudf. 572. Engl. Bot. t. 967. Tremella paluflris gela- 

 tinofa, damx cornuum facie; Dill. Mufc. CI. t. 10. f. 10.) 

 — Compreffed, much branched, gelatinous, finuated and 

 to.ithed, green ; thickened at the margin. External fila- 

 ments loofely tufted, forked, with pale pellucid tips. 



Grows on modes, in pools of frefh water. Whole plant 

 gelatinous and flippery, of a grafs green. It fecms very 

 near R. Cornu daimc of Roth, if not the fame. 



R. luberiformis. Potatoe Rivularia. Engl. Bot. t. 1956. 

 — Irregularly globofe, inflated, pale brown ; white within. 

 Seeds vertically difpofed in rows at the fummits of the fila- 

 ments. — Grows on rocks and fubmarine plants, on the fouth 

 coaft of England. When floating it looks like a group of 

 young potatoes. Each plant is hollow, confiding of a thick 

 tender coat. The outfide is not, as in the laft, covered with 

 pellucid filaments, beyond the feed-bearing part. 



R. atra. Small Black Rivularia. Roth Catal. v. 3. 

 340. Engl. Bot. t. 1798. -Hemifpherical, folitary, feflife, 

 hard, black. Internal filaments llraight, compact, branched, 

 concentric, green ; their joints cylindrical. — This is found 

 on mud, or on wooden piles, in fait marfhes, or about the 

 mouths of rivers ; confiding of black granules the fize of 

 muftard-fecd. Thefe, when highly magnified, and cut per- 

 pendicularly, are found to confiit of concentric rows, of 

 more or lefs pale, green, denfe filaments. 



R. calcarea. Calcareous Rivularia. Engl. Bot. t. 1799. 

 — Hemifpherical, feffile, clultered, hard, green. Internal 

 filaments llraight, compact, entangled, iimple, with fcarcely 

 any appearance of joints. — This is found in the beds of 

 rivers, and mountain torrents, in Ireland, Wales, &c. in 

 mades, either leparate, the Gee of a large pea, or aggregate 

 and confluent. Their colour a glaucous green ; their fub- 

 ftance firm, of fimplf parallel fibres, or tubes, .all conglu- 

 tinated, as it were, witli calcareous earth. 



R. nhinuliita. Little Hedgehog Rivularia. (Conferva 

 echinulata; Engl. Bot. t. 1378.) — Floating, glaucous, glo- 

 bofe, muricated with the points of its concentric, fimple, 

 jointed, diort filaments. - Foimd by the Rev. H. Davies, 

 in a lake, in Anglefia, covering the furfaec 111 June and 

 .Inly, with a floating mafs of little feparate prickly globules, 

 eai Ii the fize of a pin's head. 



RIVULET, a diminutive of river. 



RIXAS, in Geography, a mine-town of B1.1/.1I, in the 



government oi Goyas ; 80 miles N. ot Villa Boa, 



RIXDOLLAR, in Commerce, 1 money of account and 

 filver com in Holland, Germany, Denmark, and Sweden. 

 In Holland, a nxdollar is worth 2^ gilders, 50 divers, or 

 800 penning*. A pound Flemilh is equal to 6 gilders, or 



2. rixdollars, and is divided into 20 (hillings, 120 divers, or 



240 pence Flemilh, called alio groOtB: hence a nxdollar is 



I ' 11 equal 



