KONGL. SV. VET. ARADEMIENS HANDLINGAR. BAND. 20. N:0 5. 185 



supposition of this algologist that the plant grows attached to stones. It is probably 

 literal. 



Locality: Greenland. 



Rhodochorton Rothii (Turt.) Nag. 



Ceram. p. 355. Conferva Rothii Turt. Syst. 6, p. 1806; sec. Dillw. Brit. Conf. t. 73. 



f. typica. 

 Descr. Callithamnion Eothii J. G. Ag. Epicr. p. 13. 

 Fig. Thamnidiura Eothii Thur. in La Jol. Liste Alg. Cherb. t. 5. 

 Exsicc. » n Aresch. Alg. Scant!, exsicc. N:o 259. 



f. globosa nob. 



Planta globosa, densissime intertexta, diametro vix 2 mm., plexu basali e filis repentibns ramosis, con- 

 fertis constante, systemata ramorum, creberriraa, fastigiata, dense radiatim disposita emittente; axi primario ra- 

 raorum systematum pauUo supra basim in fasciculo ramorum soluto, ramis raro simplicibus, vulgo prsesertim 

 supra medium ramulis plus minus crebris, elongatis, adpressis, approximatis, secundis, vel alternis obsessis; arti- 

 culis inferioribus ramorum diametro fere lequilongis, circa 14 k. crassis, summis ramulorura diametro saltem 

 3-plo longioribus, vix 5 //. crassis; ramis tetrasporangiferis snbapicalibus. Tab. 15, fig. 9 — 13. 

 Syn. Callithamnion floridulum Lyngb. Hydr. Dan. p. 130, tab. 41 D. 

 » SoMMERF. Suppl. p. 193. 



» Rothii Croall, M. Disc. p. 460. 



» » Dickie, Alg. Sutherl. 1. p. 143; Alg. Cumberl. p. 239. 



» » SOMMERF. Suppl. p. 193. 



Thamnidium » Kjellm. Spetsb. Thai). 1, p. 27; Algenv. Murm. Meer. p. 25. 

 » » Kleen, Nordl. Alg. p. 22. 



Description of f. globosa. The plant forms almost globular, dense, solid tufts, 

 which are about 2 mm. in diameter and whose colour inclines to violet (fig. 9). Its 

 basal portion is composed of densely intertwisted, procumbent, branching filaments (fig. 

 10). Fro'm these there issue radially fastigiate, dense, very densely congested branch- 

 systems (fig. 11), having a short, more or less curved, main axis about 14 ju. thick at 

 the base and formed of slightly tun-shaped cells which are about as long as thick. 

 This axis is divided into a more or less dense bunch of branches which at their base 

 are of about the same thickness as the main axis or the secondary axes from which 

 they arise, but taper equally and strongly towards the tip, so that they are here scar- 

 cely half as thick as downwards. The cells are also elongated upwards, so that, from 

 being in the lower portions of these axes slightly tun-shaped and about as long as 

 thick, they become quite cylindrical and three times longer than thick (fig. 12, 13). 

 These branches are rarely simple, generally throwing out nearer the base one or two 

 and above their middle two or more, erect, appressed side-axes composed of cylindrical 

 cells, attaining the same height as their respective primary axis and tapering upwards 

 like this, though only slightly. The branches bearing tetrasporangia seem to be subapi- 

 cal as in the typical form. The present form differs from this by its habit and richer 

 branching and by the cells being different as to size, length, and thickness in the upper 

 and lower part of the frond. 



K. Vet. Akacl. Handl. Bd. 20. If:o 0. ^^4 



