THE ALGAE OF BERMUDA. 141 



d'une couleur plus rose. Elle s'en distingue surtout, parce que ses 

 pinnules, lorsqu'elles sont bien developpees, portent des pinnules de 

 second ordre sur leur bord superieur et que les tetraspores sont divises 

 en croix." The tetraspores in the Bermuda plant are distinctly 

 tripartite. As a secondary distinction we would note that a prostrate 

 axis can become erect and an erect axis prolong itself and either de- 

 velop a new branch system at some distance from the old, or be trans- 

 formed into a prostrate axis. 



The type specimen of the species is No. 7521 in the Collins her- 

 barium; from the cave at Gravelly Bay, collected by Hervey in April, 

 1913. 



ANTITHAMNION Na'geli. 



A. CBUCIATUM (Ag.) Nageli, 1847, p. 200; P. B.-A., No. 2191 

 CaUithamnion cruciatum Agardh, 1827, p. 637; Harvey, 1846-51, PL 

 CLXIV. Abundant and luxuriant on an old wreck, Castle Harbor, 

 St. George's, April, on rock, Spanish Point, March, May, small form 

 in cave, Gravelly Bay, Dec., Hervey. 



Var. radicans (J. Ag.) comb, nov.; 19 P. B.-A., No. 2047; A. crucia- 

 tum F. radicans Hauck, 1885, p. 71; CaUithamnion cruciatum var. 

 radicans J. G. Agardh, 1841, p. 44. Creeping on perpendicular or 

 overhanging rocks between tides, North Shore opposite Gibbet 

 Island, Aug., Collins; Dec., Hervey. The main axis is prostrate, 

 about 40 /j. diam., the cells cylindrical, 2-5 diam. long; near the upper 

 end of each cell is a pair of opposite branches; whorled branches were 

 not seen. Successive pairs of branches are not in the same plane, 

 but are more or less exactly decussate. The lower cell of each branch 

 is short, no longer than broad, more or less rounded; the following 

 cells are 2-4 diam. long, growing shorter upward; the diam. at the 

 base of the branch, 20-25 /JL. The short basal cell often bears a long, 

 simple, rhizoidal branch, the cells up to 10 diam. long, about 15 /j. diam., 

 of paler color than cells elsewhere in the plant; the terminal cell of 

 this rhizoid may form a discoid expansion, attaching itself to the 

 substratum. All normal branches, whether issuing from the upper 

 or the lower surface of the main filament, turn upwards ; their branch- 

 ing is always alternate, a ramulus from each cell, all nearly or quite 



19 This combination occurs in Collins, 1900, p. 48, attributed by error to 

 J. G. Agardh. No synonymy being given, it can hardly be considered a 

 publication. The difference from the typical A. cruciatum seems too great 

 to consider it as a form, as was done by Hauck. 



