RHAGADOSTOMA. 



[ 656 ] 



RHIZOCLONIUM. 



RIIAGADOS'TOMA, Korb. A genus 

 of Micro-lichens parasitic on the thallus of 

 Solorina crocea. Spores 2-4, in lanceolate 

 fugacious thecae, large, simple, becoming 2- 

 locular, colourless. (Lindsay, Qu. Mic. Jn. 

 1869, 344.) 



RHAPHIDOGL(E'A,Kutz. Agenusof 

 Diatomaceae. 



Char. Frustules navicular, arranged in 

 radiating crowded rows in a globose gelati- 

 nous mass. Marine. 



R. micans (PI. 19. fig. 11). Rows of frus- 

 tules irregular, obsolete ; valves linear-lan- 

 ceolate, subulate, somewhat acute. Length 

 1-140". 



Three other species. 



BIBL. Kutzing, BarilL 10 ; id. Sp. Alg. 97. 



RAi'HIUOMONAS, Stein. A genus of 

 Flagellate Infusoria. Free, green, Hagellum 

 single ; mouth anterior, with a defined pha- 

 rynx ; an anterior row of trichocysts. R. 

 semen = Monas s. } Ehrb. ; length 1-500"; 

 marsh-water, among decaying Sphaynum. 

 (Kent, Inf. 391.) 



RHAPHONE'IS, Ehr. A genus of Dia- 

 tomacese. 



Char. Frustules single, quadrangular, na- 

 vicular ; valves without a median aperture 

 (nodule?) ; median sutural line longitudinal. 

 Marine. = Doryphora without a stalk. 



Eleven species. 



BIBL. Ehrenberg, Ber. Berl. Akad. 1844, 



74 ; Kiitzing, Sp. Alg. 49. 



"~NOPS, 

 torift. 



RHINOPS, Hudson. A genus of Rota- 



BIBL. Hudson, Ann. Nat. Hist. January 

 1869. 



RHINOT'RTCHUM, Oorda. A genus of 

 Mucedines (Hyphomycetous Fungi), cha- 

 racterized by more or less clavate threads 

 studded with spicules, to which the spores 

 are attached, Several species occur in this 

 country. A very beautiful rose-coloured 

 species has lately been gathered in rabbits' 

 dung. 



Nematozonum, Desm., differs in bearing 

 necklaces of spores. 



BIBL. Berk. Outl 348; Cooke, Handb. 

 590. 



RHIPIDODEN'DRON, Stein. A genus 

 of Flagellate Infusoria. Bodies ovate, con- 

 tained in elongated parallel, granular tubes, 

 forming a branched zoary. Two species; 

 freshwater. (Kent, Inf. 285.) 



RHIPIDOPH'ORA, Kiitz. A genus of 

 Diatornacese. 



Char. Those of Licmophora, except that 

 the frustules are each furnished with a 



distinct stipes ; but as this is not always the 

 case, the character is of little or no value. 

 Marine. 



Three British species (Smith) ; twelve 

 others (Kutzing). 



R. paradoxa (PI. 17. fig. 19). Stipes fili- 

 form, dichotomous ; frustules in front view 

 broadly wedge-shaped, somewhat acute at 

 the base. Length of frustules 1-540 to 

 4-480". 



RHIZAMTSIINA, Brady. A thread-like 

 Foraminifer, or chitino-arenaceous branch- 

 ing tube (1-50" diam.), forming a tangled 

 weed-like tuft. H. algaformis, from 2160 

 fathoms near Juan Fernandez. (Brady, Jn. 

 M. Soc. n. a. xix. 39.) 



RHIZID'IUM, Braun. A genus of Uni- 

 cellular Algae, allied to Chytridium. At 

 first unicellular, then bicellular, and with 

 delicate multipartite rootlets ; cells oblong ; 

 fructiferous cells beneath the apex ; zoo- 

 spores with a cilium. Parasitic in Euglence 

 and NiidlcB. 



BIBL. Braun, Monatab. 1856, 591; Ra- 

 benht. Alg. iii. 284. 



RHIZ'INA, Fr. A genus of Helvelloidei 

 (Ascomycetous Fungi), distinguished from 

 Peziza by the bullate hymenium, con- 

 cave beneath, and furnished with rooting 

 fibrils. 



Two species have been found in this 

 country, on sandy banks where the heath 

 has been burnt. 



BIBL. Fr. Syst. Myc. ii. 33 ; Currev, Linn. 

 Tr. xxiv. 493 ; Cooke, Handb. 664. 



RHIZOCLOTsTIUM, Kiitz. A genus of 

 Confervaceae (Confervoid Algae), distin- 

 guished by the decumbent habit and the 

 short, root-like appendages to the branches. 



Kutzing includes here many of our British 

 Confervas : 



R. rivularc, C. Filaments simple, diam. 

 1-900", fine bright-green bundles 2 to 3 feet 

 long ; in streams and rivers ; common (Dill- 

 wyn, pi. 39). 



R. tortuosum, Dillw. Filaments simple, 

 diam. 1-800", rigid, curled and twisted, 

 forming large strata; in salt-water pools; 

 abundant (Dillwyn, pi. 46). 



R. arenosum, Carm. Filaments simple. 

 diam. 1-1000 to 1-1800"; in dirty-green 

 strata ; sandy sea-shores. 



R. obtusangulum, Lyngb. (PI. 9. fig. 12). 

 Filaments branched, diam. 1-1400"; pale- 

 green, stratified ; sandy sea-shores. 



R. riparium (Jergensii, Kiitz.). Fila- 

 ments branched, diam. 1-1400 to 1-1800". 

 Apparently not distinct from the preceding. 



