REBOUILIJA. 



[ 054 ] 



REPTOMONAS. 



from the anterior margin ; foot decurved, 

 lunate; freshwater; length 1-288". 



BIBL. Ehrenberg, Infus. 448 ; Pritchard, 

 Infusoria, 688. 



'REBOUIL'LIA, Raddi. A genus of 

 Marchantieae (Hepaticae), founded on Mar- 

 chantia hemisphcerica, Linn., characterized 

 by the conical or flattened, !- 5-lobed stalked 

 receptacle (fig. 616), the perigone being ad- 

 herent to the lobes of the receptacle on the 

 under side, opening by a slit (fig. 617) ; 



Fig. 616. 



Fig. 617. 



Hebouillia hemispherica. 



Female receptacles, with the perigone burst. 



Fig. 616, seen from above ; Fig. 617, from below. 



Magnified 2 diameters. 



perichjete none, and the globose sporange 

 bursting irregularly. The antheridia are 

 imbedded in sessile, crescent-shaped disks. 

 The fronds are rigid, with a well-marked 

 midrib, green above, purple beneath. It 

 grows on moist banks, or by the side of 

 mountain-streams. 



BIBL. Hook. Br. Fl ii. pt. 1. 108 ; Bis- 

 choft', Nova Acta, xvii. 1001, pi. 69. fig. 1 ; 

 Endlich. Gen. Plant. No. 468. 



RECEPTACLES FOR SECRETIONS. 

 See SECRETING ORGANS of Plants. 



RED SNOW. The remarkable pheno- 

 menon known under this name has been the 

 subject of very extensive investigation, and 

 it is well known to be the result of the 

 enormous development of a microscopic 

 organism related to Pi'otococcus or Chlami- 

 dococcus viridis. We are inclined to believe 

 that more than one form is comprehended 

 at present under the name of Protococcus or 

 Hcematococcus nivalts; for our specimens of 

 Arctic red snow, for which we were in- 

 debted to the kindness of R. Brown, appear 

 to belong to the same genus as Palmella 

 cruenta, as first indicated by Brown, and 

 confirmed by Sir W. Hooker. Greville's 

 figures of the Scotch plant closely resemble 

 this ; but the continental plants described by 

 Shuttle worth and others would seem conge- 

 neric with Protococcus, Chlamidococcus, and 

 Chlamidomonas, since they produce active 

 zoospores, the forms which Shuttleworth 



described as distinct Infusoria, as species of 

 Astasia. Nearly connected with this con- 

 tinental snow-plant, if not identical, is the 

 Protococcus pluvialis, described so elaborately 

 by Colin, which moreover appears to be 

 synonymous with the Discercca purpurea of 

 Morren. 



The following is a description of the i 

 snow, brought home by Capt. Parry, from 

 our own observation. It may be noticed as 

 remarkable that, after being' kept so many 

 years in a moist state in a stoppered bottle, 

 the structure appears almost unrhn> . 

 only difference being the assumption 

 green colour on the surface of th> 

 when exposed to light. Frond an indefinite 

 gelatinous mass densely filled with spherical 

 cells, about 1-200" in diameter (PI. 7. tig. 

 3d) ; cells with a distinct membrane, their 

 contents consisting of numerous tolerably 

 equal granules, red or green (see ab<>\ 

 Between the large cells lie patches of nii- 

 nute red granules (as in Palnn-fln cruenta, 

 PI. 7. fig. 3 a, b), apparently dischai -ged from 

 the large cells. Bauer and (ireville both 

 describe this as the mode of propagation of 

 the plant; but it is probable that the ( 

 also increase by division when acth 

 getating. 



BIBL. Brown, Appendix t<> Ross's 1.^ 

 Voyage, 1819; Det'andolle, Bihl. miiv. 

 Geneve, 1824 ; Hooker, Append, to J'urry's 

 Second Voyage ; Greville, Cn/pl. Fl. pi. i':!! ; 

 Shuttleworth, JJibl. univ. Geneve, 1840; 

 Morren, Mem. Acad. L'r/r.rclle*, \i\. 

 Flotow, Nora Acta, xx. 11; Colin, front 

 Acta, xxii. 60-">. 



RENULI'NA, Blake. Minute Pubgld- 

 bular, hollow, calcareous bodies, 1-200" in 

 diameter, often silicified, entering largely 

 into the composition of the Coralline Oolite ; 

 regarded as probably organic by Sorby, and 

 referred to the Foraminifera by Blake. 

 (Sorby, Qu. Geol. Jn. vii. 1851, 1 j Blake, 

 Jn. Mic. Soc. 1876, 262.) 



RENULI'TES, Lam. (Xenulfna, Blain- 

 ville). A broad, reniform modification of 

 Vertebralina, one of the Porcellaneous Fora- 

 minifera. 



BIBL. Carpenter, Introd. For. 74. 



RE'OPHAX, Montfort. A simple, uui- 

 serial subspecies of Lituola, straight or curved, 

 chambers often angular or nigged in outline. 

 Abundant in many seas. (Parker and 

 Jones, Ann. N. H. 3. vi. 346 ; Brady, Qn. 

 Mic. Jn. n. s. xix. 51.) 



REPTOMONAS, Kt A genus of Rhizo- 

 Flagellate Infusoria. Creeping; fiagellum 



