THE ALGAE OP BERMUDA. " 87 



Gates Bay, March, Gibbet Island, April, Hervey. In the Bermuda 

 material identified with this species the frond is smaller throughout 

 and generally more delicate than in P. variegata, averaging much the 

 size and consistency of P. sanctae-crucis, and with a similar calcareous 

 coating. Tetrasporic fruit was well developed on the material from 

 both stations noted above. Sterile plants resembling the two species 

 just mentioned abound in warm shallow water, but can be distin- 

 guished only by sectioning and counting the layers of cells. In P. 

 Pavonia the sexual plant, which we have not found here, is monoecious ; 

 in P. variegata it is dioecious, in both it is rare. While all American 

 forms of Padina were formerly placed under P. Pavonia, this seems to 

 be the first occurrence of the species on this side of the Atlantic. The 

 material from Florida distributed as P. Pavonia, P. B.-A., No. 1442a, 

 and that distributed as P. Dmmllaei, P. B.-A., No. 580b, should be 

 referred to P. variegata; 1442b to P. gymnospora. The plant distrib- 

 uted as P. Durvillaei, 580a, closely resembles P. gymnospora, but in 

 the specimens now accessible the frond is uniformly two cells thick, 

 which would bring it under P. australis Hauck; but Mme. Weber, 1913, 

 p. 180,' suggests that the latter may be only a form of P. gymnospora. 

 The true P. Durvillaei Mont., appears to be found only in the Pacific. 



3. P. VARIEGATA (Lamour.) Hauck, 1887, p. 42;"^ P. B.-A., No. 

 2083; Borgesen, 1914, p. 205, figs. 157-161; Dictyota variegata 

 Lamouroux, 1809, p. 331. Kemp, May, June, July, as P. Pavonia; 

 Shelly Bay, Harris Bay, Jan., Gibbet Island, Jan., Nov., Dec, Hervey; 

 Inlet, July, Aug., Collins. Very variable in form, from orbicular 

 and undivided up to 15 cm. diam., to fronds split into innumerable 

 strips, or with many rounded proliferations; in texture from thin and 

 papery to thick and tough. It is however always darker than the 

 two preceding species, and with less conspicuous calcification, and 

 it is more than two cells in thickness, except at the growing edge, and 

 may be six layers in the older parts. Tetrasporic fruit is rather 

 common, oogonia infrequent; antheridia are known in this species, 

 but we ha;ve not found them here. 



4. P. GYMNOSPORA (Kiitz.) Vickers, 1905, p. 58; 1908, PI. VII; 

 Borgesen, 1914, p. 202, figs. 155-156; Zonaria gymnospora Kiitzing, 

 1859, p. 29, PI. LXXI, fig. 11. Farlow, 1881, without exact station. 

 Observed once only, but in good condition and fruit. Characterized 

 among our species by the absence of indusium, the frond with one 

 layer of small cells and one layer of large in cross section, the larger 

 cells sometimes dividing so as to give a section of three cells; the spore 

 bands in the center of every second space between hair bands. 



