RHODOPHYCE^. Ill RHONE. protruding fruits reseiiililiiig urns (Polysipli- onia. Fig. 2), others are pinnatily branched (Ptilota), others with ineurveil tips (C'erami- FlG. 1. llKlt ALG.E. ■ 1. Nemalion, sexual branches, showing antheridia (a) and carpogonium (6) with trichog.vne to which two sper- m.atia are attached, bep:inning of a cystocarp (e). and an almost mature cystocarp (r7); 2, Callithanmion, show- ing- sporangium (a) and three discJiarged tetraspores (b). um ) . jMost of the filamentous and membranous species, especially those which grow in quiet waters, are very delicate. Many forms on surf- beaten coasts develop large and strong car- tilagirious fronds. Sev- eral of these firmer forms yield a jelly when placed in hot water ; for instance, agar-agar is derived from species found in Ceylon, Java, and iladagascar,and Chon- drus crispus furnishes most of the 'Irish moss' used in cookery. These preparations consist mainly of mu- cilage of little or no nutritive value, de- rived from intercellu- lar spaces and swollen cell-walls. Perhaps the most remarkable group of the RhodophyceiE is the Corallines, ' with highly specialized fruc- tifications and tetra- spores borne in differentiated coneeptacles. Some are branched, with jointed segments, others have the form of convoluted nodules. They are so in- crusted and pervaded with lime as to resemble coral. Consult: Engler and Prantl, Die natilrlicken FlQ, 2. POLYSIPHONIA. Showing branching, a cysto- carp (a), and escaping spores (fc). I'flanzenfamilien (Leipzig, 1887 ct scq.) ; Murray, Introducliiin to ihf Study uf .Sco itttti* (LunduD, 1S!1.">). RHODO'PIS (Lat., from Gk. •Poawiii). A famous Greek courtesan, ii native of Thriice. At one time she was a fellow slave of the poet -Esop. Later she was carried to Xaucratis. in Egjpt. While she plied the tra<Ie of hetjrra there Charaxus, brother of Sappho, fell in love with hor and ransomed her at a great price. She was attacked by Sappho in ii poem, .fter her libiraliuii sin- luntinued to reside in Xnuerutis. RHOMBOID. See Paraixelouk.m. RHOMBUS. See Paralmlockam. RHONDDA, rdnd'da. An important and pop- tilnus coal-mining district, now a muniiipality of (ilamorgansliire, Wales. It is situated amid pic- turcsmie vallev scenery on the Khondda River, near ^Ierthvr 'Tydfil. "Population, in 1891, 88,- .3.50; in liKl'l, 113,700. RHONE, r&n (Fr. Rhone; Lat. Ithodanua) . The princijial river of Soutlieastern France. It rises at an altitude of 75.50 feet in the Rhone Glacier on the south slope of the Dammastock, a peak of the Urner Alps in South Central Switzerland (Map: France, L 7). It Hows first in a general southwest course through Southern Switzerland and into France as far as Lyons, then due south until it empties into the Gulf of L.yons in the Mediterranean Sea, 25 miles west of Marseilles. Its length is 504 miles. Its upper course is through the great valley lying between the Bernese and the Pennine .Mps, which forms the Swiss Cantcm of Valais. Here it grows rapidly by taking up a number of short but vol- uminous mountain torrents fed by the great gla- ciers which cap the mountain ranges (ni either side. At Martignj' the valley is narrowed and the river makes a sharp turn to the northwest, becomes then navigable below Saint-Maurice, and enters the eastern end of Lake Geneva. It leaves the lake at its western end at Geneva, resum- ing its southwest direction, quits Swiss ter- ritory, and soon after passes throvigh the Jura Range in a deep and narrow gorge, where its width is decreased from 350 to 25 yards. Here it fornuniy disappeared through a subterranean channel known as the Perte du Rhone, but the rocks which covered it were removed in 1828. After leaving the gorge it becomes again navi- gable, and remains officially so to its mouth. Its fall from Lyons to the sea, a distance of 208 miles, is over 500 feet, or 21,1. feet per mile. Its cour.se below Lyons lies in a broad, fertile, and beautiful valley between the -Alps and the Cfivenncs. It receives here two large tributaries, the Isfere and the Durance, the latter joining it at .A.vignon. below which town the river Hows through a sandy and arid tract which was for- merly a gulf of the sea. Its delta, who.se main arms are the Grand and the Petit Rliiine. which form the He de la Camargue (see not:cnES-Di'- Rhoxe). is growing at the rate of nearly 200 feet annually, owing to the large quantities of sediment carried by the stream. The navigation of the Rhone, owing to the swift current, the shifting of the bed, and the numerojis isl.ands, is very diOicnll even for steamers, and especially on the up- stream route. Extensive regulating works have to some extent improved the waterway above the delta, and the shifting and sand-barred mouths of the latter have been obviated by a short canal
