330 TUFTS COLLEGE STUDIES, VOL. II, No. 3 



Distinguished from R. hieroglyphicum by the thick membrane, 

 firmer substance, and short cells. 



9. R. FONTANUM Kutzing, 1843, p. 261 ; 1853, PI. LXXIV ; 

 R.fontinaleVJo\\z, 1887, p. 144, PI. CXXI, figs. 22-25. Fila- 

 ments 12-22 p. diam., cells 2-4 diam. long, membrane thickish ; 

 branches usually abundant, mostly pluricellular. Me., Mass., 

 Pa., 111., Porto Rico. Europe. 



10. R. HOOKERI Kiitzing, 1849, p. 383; 1853, PL L,XVII, 

 fig. 3 ; Hohenacker, Meeresalgen, No. 477. Filaments stiff, 

 usually 70 yu, diam., sometimes up to 90 /u.; cells 2-4 diam. long, 

 wall thick, 4-10/4; branches sometimes few, sometimes many; 

 often pluricellular, occasionally having branches of a second 

 order. W. I. So. America, Africa, Asia. 



A stout species, approaching Cladophora in its characters. 



11. R. CRASSIPELLITUM var. ROBUSTUM G. S. West, 1905, 

 p. 283. Filaments crisped, occasionally ventricosely inflated, 

 curved and genuflexed ; about 70 /u diam., cells 1^-2 diam. 

 long, walls very thick and stratified, up to I3/"-; apical cells 

 somewhat attenuate and rounded, basal cell often inflated and 

 producing rhizoids ; no other branching. Forming mats on 

 damp earth. W. I. 



R. crassipellitum W. and G. S. West, i897a, p. 35, with fila- 

 ments 33-43 p- diam., wall 9-13 p. thick, is found in W. Africa.* 



* W. and G. S. West, 1895, p. 265, PI. XIV, figs. 17-24, describe R. Berg- 

 grenianum var. dominicense ; filaments densely intricate, slender, cells 

 9-10 yu diam., 2-3 diam. long, wall usually thin, a large proportion of the 

 cells with short, very obtuse, usually unicellular or continuous branches. 

 In hot water stream in crater of volcano, Dominica. The typical R. 

 Berggrenianum occurs in New Zealand, and is much like some forms of 

 R. hieroglyphicum, but has akinetes 16-20 /j. rtiam., 1-3 diam. long; it 

 may be merely the akinete- producing form of J?. hieroglyphicum. West's 

 plant is probably an abnormal form, due to the hot water, etc. ; as it has 

 no akinetes, its connection with R. Berggrenianum is doubtful. 



G. S. West, 1905, p. 283, reports from Barbados R. hieroglyphicum 

 var. Kochianum (Kiitz.) Stockrnayer, giving the dimensions as diam. 

 23-29 n, cells i>-2 diam. long. This would seem to agree better with the 

 type, as Stockrnayer gives 12-13 /JL for the diameter of var. Kochianum. 



R. occidental Kutzing, 1853, P- 22, PI. LXIX. fig. 5, from Trinidad, 

 seems from plate and description to be hardly distinguishable from R. 

 hieroglyphicum. R. hieroglyphicum var. atrobrunneum Tilden, 1898, p. 

 90, PI. VIII, figs. 14-17, from Yellowstone Park, hardly seems to have 

 enough distinctness from the type to deserve a name. Four species in 

 Wolle, 1887, must be considered doubtful ; R. stagnate, R. fluitans, R. 

 Casparyi and R. majus. From the plate CXXI, figs. 26-28, R. fltt,itans 

 might be considered as a synonym of R. crispum Kiitz. ; but a specimen 

 marked R.fiuitans by Wolle proves to be Microspora amoena (Kiitz.) 

 Rab. If R. slagnale is the same as R. stagnorum Wolle n. sp., Raben- 

 horst Algen, No. 2577, it is probably a coarse short-celled form of R. 

 h icroglyph icu m . 



