Contribution. I. 45 



Gen. Antithamnion (Nag.) Thur. 

 in Le Jol. Liste Alg. Ckerb. p. Ill; Nag. Algensyst. p. 200; char. mut. 



Antithamnion floccosnm (Mull.) Kleen. 

 NordL Alg- p. 11; Conferva floccosa Mflll. Fl. Dan. t. 328. fig. 1. 



f. atlantica J. G. Ag. 

 Descr. Callithamnion floccosam var. a atlanticum J. G. Ag. Epicr. p. 22. 

 Fig. „ „ Harv. Phyc. Brit. t. 81. 



This alga is litoral as well as sublitoral. In the litoral 

 zone it occurs on rocks at low-water, covered by other algse, 

 or in deep and shady rock-pools between tides, most rarely 

 epiphytic. I have found a solitary specimen on Bhodomela 

 lycopodioides and on Halosaccion ramentaceum, in the latter 

 case in a rock-pool where both species grew side by side in 

 rather considerable abundance. Scattered individuals have 

 also been found attached to Lithotliamnia within the subli- 

 toral region on a depth of 3 — 5 fathoms. It seems not to 

 descend to a greater depth. The plant appears almost only 

 on open shore, and it thrive best in much exposed localities, 

 growing spread, or sometimes gregarious in considerable 

 number. The specimens are generally small. But at Sylte- 

 fjord I met with luxuriant ones reaching a length of 8 cm., 

 and at Berlevaag I found it in great number on an iron 

 buoy, which was laid out in the summer 1885, and put on 

 shore for cleaning in July 1887. The greatest part of the 

 specimens here collected were large and well developed, at- 

 taining 10 cm. in length. Here the plant grew associated 

 with Antithamnion boreale, A. P'tfiaiscei, Polysiphonia urceolata 

 and a few other algse. 



The present plant has usually been found sterile. But 

 those specimens collected at Berlevaag, in the middle of July, 

 were richly tetrasporiferous, yet only a few of them fully 

 developed. It has been found at Scotland bearing sporo- 

 carps in April and May. Cp. Traill, Monogr. Appendix. 



Distribution: Generally scattered and scanty along the 



