RHIZOGLYPHUS. 



[ 657 ] 



RHIZOSELENIA. 



On sandy sea-shores ; not uncommon (Engl. 

 Botany, pi. 2100). 



It. impkxum, Dillw. Filaments simple, 

 diam. 1-2000"; bright green; forming large 

 strata, on mountain-rocks (Dill. C. im- 

 plex a, tab. B). 



R. arenicolum, Berk. (Kochianum, Kz.). 

 Filament 1-2000 to 1-2400"; mountain- 

 rocks (Berkeley, Gleanings, pi. 13. fig. 3). 



BIBL. Harvey, Mar. Alg. 206, pi. 24 F ; 

 Kiitz. Sp. Alg. 385 ; Tab. Phyc. ; JBr. Fl. ii. 

 pt. 1.354; Dillwyn,.Z?r. Conferva; Rabenht. 

 Alg. iii. 329. 



RHIZOG'LYPHUS. See ACARUS, p. 5. 



RIIIZOMOR'PHA. The name given by 

 authors to certain mycelioid expansions with 

 a dark bark, which have been traced to 

 Polypori and Sphceriacei. Many of the 

 forms which occur in mines are remarkable 

 for their luminosity. 



BIBL. Berk. Int. Crypt. Sot. p. 266. 



RHIZONE'MA, Thw. A genus of Oscil- 

 latoriaceae (Confervoid Algae) = Dictyonema, 

 Kiitz. This curious plant (It. inter ruptum) 

 differs from its allies by the gelatinous 

 sheath being composed of distinct cells and 

 furnished with branched root-like processes, 

 which anastomose freely. The cell-contents 

 are deep blue-green, with occasional yel- 

 lowish interstitial cells. 



BIBL. Thwaites, Eng.Bot. Supp. pi. 2954; 

 Kiitz. Sp. Alg. 321; Tab. Phyc. ii. pi. 40. f. 5. 



RHIZOPHOR A'CE^E. A family of Di- 

 cotyledonous plants, to which belong the 

 celebrated Mangrove-trees of the tropics. 

 They are remarkable for the general occur- 

 rence of a ramified form of liber-cell (PI. 48. 

 fig. 31). The long woody radicles pushed 

 out by the fruits, while still attached to the 

 parent tree, contain a vast number of these 

 ramified cells with very thick walls. 



RHIZOPHYD'IUM, Schenk, = Chytri- 

 dium, sp. 



RHIZOP'ODA, Duj., or better, Psettdo- 

 poda, Ehr. A Class of the animal subking- 

 dom Protozoa. 



Char. Gelatinous, structureless aquatic 

 animals, mostly minute, locomotive organs 

 consisting of variable retractile root-like 

 processes pseudopodia or false legs ; no 

 mouth. 



The food-particles are drawn into the 

 body by the pseudopodia, as described under 

 Actinophrys. The body is sometimes naked, 

 at others enclosed in a carapace or external 

 skeleton, which is either chitinous, calca- 

 reous, or siliceous. A nucleus and a con- 

 tractile vesicle are sometimes present, some- 



times absent. In some, the protoplasm 

 contains granules and yellow cells; these 

 have been supposed to be parasitic orga- 

 nisms, a rudimentary form of liver, .or re- 

 productive organs. The presence of the 

 contractile vesicle in some Rhizopoda, and 

 its absence in others, is entirely opposed to 

 the view of Stein and Kent, that the 

 presence of a contractile vesicle is a cha- 

 racter of anirnality; unless many of the 

 Rhizopoda be referred to the Vegetable 

 Kingdom. The Class is divided into four 

 Orders, thus : 



RETICTJLARIA. Pseudopodia slender, 

 anastomosing to form meshes. Foramini- 

 fera, Lieberkiihnia, Labyrinthula, &c. 



RADIOLABIA. Pseudopodia radiating. 

 Actinophryina, Acanthometra, Polycystina, 

 Thalassicolla. 



LOBOSA. Pseudopodia short, variable, 

 not anastomosing. Amoebaea, Arcellina. 



GBEGABINIDA. Pseudopodia absent ; 

 these are often considered a distinct Class 

 of Protozoa. 



BIBL. Dujardin, Ann. Sc. Nat. i., iii.,iv. ; 

 Schultze, PolythaL, 1834; Carpenter, Phil. 

 Tr. 1856, 1859, 1862 ; Huxley, Invertefoata; 

 Williamson, Tr. Mic. Soc. 1852, 169, and ii. 

 159 ; Reichert, Ann. N. H. x. 1862, 401 ; 

 Kclliker, Zeitschr. wiss. Zool. 1849; Lie- 

 berkiihn, ibid. 1856, 308 ; Carter, Rhizopoda 

 ofEng. 8f India, Ann. N. H. 1865 ; Tr. Mic.' 

 Soc. 1849, 174 ; Miiller, Mull. Archiv, 1858 ; 

 Focke, Physiol. Stud. 1854; Fresenius, Beitr. 

 z. mikr. Organ. 224; Miiller, Monatsb. Akad- 

 Berlin, 1856 ; Bailey, Americ. Journ. Sci. xv.; 

 Claparede & Lachmann, Infus.; Haeckel, 

 Radiolarien, 1862; Gener. Morphol. ; Archer, 

 Qu. M. Jn. 1870-78; Hertwig & Lesser, 

 Arch. mik. An. 1874, x. Suppl.; Schultze, 

 ibid, x., xi., xiii. ; Hertwig, Radiol. (Histol.) 

 1876; Wallich, M. M. Jn. xiii. 210; Ann. 

 N.H. 1877, xix. 158 ; Claus,Zoo%wj; Leidy, 

 Freshw. Ehiz. N. Amer. 1879 ; Jn. Mic. Soc. 

 1880, 288; Butschli, Bronn's Klass. $c. 

 1880 (# the Bibl. therein}-, Cienkowski, 

 Schnitzels Archiv, 1876, xii. (new genera) : 

 Pascoe, Zool. 1880, 6. 



RHIZOPO'GON, Fries. A genus of 

 Hypogaei (Gasteromycetous Fungi). R. ru- 

 bescens is found in sandy ground. (PL 27. 

 fig. 8, sporophores). 



RHIZOSELE'NIA, Ehr. A doubtful 

 genus of Diatomaceae. 



Char. Frustules elongate, subcylindrical, 



marked with transverse or spiral lines, ends 



oblique or conical, and with one or more 



long terminal bristles; marine and fossil. 



2u 



