170 KJELLMAN, THE ALG^ OF THE ARCTIC SEA. 



Ceramium rubrum (Huds.) Ag. 



Disp. Alg. p. 16. Conferva rubra Huds. F1. Angl. p. 600. 



f. decurrens J. G. Ag. 



Spec. Alg. 2, p. 127. 

 Descr. Ceramium rubrum a decurrens J. G. Ag. Epicr. p. 100. 

 Exsicc. » decurrens Aresch. Alg. Scand. exsicc. N:o 208. 



f. genuina. 



f. interstitiis et juvenilibus et adultis densius corticatis; ramis lateralibus paucis, conformibus, diciiotomis. 



f. prolifera J. G. Ag. 



Spec. Alg. 2, p. 127. 

 Descr. Ceramium rubrum /? proliferum J. G. Ag. Epicr. p. 100. 

 Fig. » secundatum Lyngb. Hydr. Dan. t. 37 A. 



» botryocarpum Haev. Phyc. Brit. t. 215. 



f. pedicellata Duby. 



sec. J. G. Ag. Spec. Alg. 2, p. 128. 

 Descr. Ceramium rubrum /; pedicellatum J. G. Ag. Epicr. p. 101. 

 Fig. » » KiJTZ. Tab. Phyc. 13, t. 4, fig. a. et b. 



f. squarrosa Harv. 

 Ner. Am. 2, p. 214. 

 Descr. Ceramium rubrum e. squarrosum Hauv. 1. c. 

 Fig. » » f. squarrosa tab. nostra 15, fig. 7. 



Syn. Ceramium rubrum J. G. Ag. Spetsb. Alg. Progr. p. 2; Bidr. p. 11. 

 B » Croall, pi. Disc. p. 460. 



» » Gobi, Algenfl. Weiss. Meer. p. 46. 



» « Kjellm. Spetsb. Thall. 1, p. 25; Algenv. Murra. Meer. p. 23. 



B » Kleen, Nordl. Alg. p. 20. 



B » Nyl. et Sael. Herb. Fenn. p. 74. 



» » virgatum Post, et Rupe. 111. Alg. p. II. 



Conferva diaphana Wg. PL Lapp. p. 511. 



Remark on the definition of the forms. Ceramium rubrum, in the Polar Sea as well 

 as elsewhere, is multiform. The rather few specimens from the former region which 

 I have had the opportunity of examining, appear however to be referable to the above- 

 mentioned forms. The specimens determined by me as being f. decurrens are in all 

 essential points similar to those from the northern portion of the Atlantic. This form 

 is easily known by its articular cells being at first uncorticated, by the absence of 

 prolification and by its poverty in lateral branches, which, if existing, branch in the 

 saTne manner as the main axis. Besides, the frond is more strongly attenuated upwards 

 than in any other form. The form designated by me as f. genuina resembles the former 

 in habit, branching etc., but differs from it by its darker colour and the strongly 

 corticated articular cells. Nearest this there stands a robust and large-sized form, well 

 represented by fig. n, table 4 in Kutzing's Tab. Phyc. 13 and certainly belonging to 

 the same series of forms of Ceramium ruhrum as the plant figured pi. 181 in Harv. 



