128 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 12 



the sheaths hyaline, thin, firm or diffluent, coloring blue when treated 

 with chlor-zinc-iodine, the trichomes 6-12 /x broad, slightly constricted at 

 the crosswalls, rounded at the tips, the cells quadrate and longer and 

 shorter than broad. 



Mexico: Is. Revilla Gigedo, in a high sandy tide pool, Sulphur Bay, 

 I. Clarion, no. 39-15, 17 Mar. 1939. 



LYNGBYA C. Agardh ex Gomont, 1892 

 Lyngbya epiphytica Hieronymus 



Drouet 1936, p. 24, fig. 8. 

 Ecuador : I. Wenman. 



Lyngbya aestuarii Gomont 



Tilden 1910, p. 120, pi. 5, figs. 40, 41 ; Fremy 1939, p. 27. 



Plant a pannose green, blue-green, black, or brownish stratum on soil 

 wet by sea or rain water, or a coarsely and radiately fibrous mat sub- 

 mersed in fresh or sea water, the filaments coarse, straight or entangled, 

 the sheaths hyaline and thin at first, becoming thick, lamellose, and 

 internally yellow, brown or almost black, never coloring blue when 

 treated with chlor-zinc-iodine, the trichomes 10-24 {x broad, cylindrical, 

 not constricted at the crosswalls, slightly attenuated at the tips, the cells 

 very short, the crosswalls marked on each side with a row of conspicuous 

 granules, the apical cells rounded truncate, the outer membrane conspicu- 

 ously thickened. 



Mexico: Is. Revilla Gigedo, from an upper tide pool, Braithwaite 

 Bay, I. Soccoro, no. 39-53, 18 Mar. 1939. 



Lyngbya majuscula Gomont 



Tilden 1910, p. 123, pi. 5, fig. 42; Taylor 1928, p. 44, pi. 1, fig. 19; 

 Fremy 1939, p. 28. 



Plant a greenish, brown, or black mat of coarse tangled threads free 

 in marine situations, or entangled with attached algae, less often forming 

 a fibrous-pannose stratum on rocks, the filaments contorted and much 

 mtertwined, not seldom straight and parallel, the sheaths hyaline, at first 

 thin, becoming thickened, roughened, and lamellated in age, never color- 

 ing blue when treated with chlor-zinc-iodine, the trichomes 15-60 fi broad, 

 not constricted at the crosswalls, the cells very short, the crosswalls not 

 granulated, the apical cells rounded. 



Mexico : Is. Revilla Gigedo, in high sandy tide pools. Sulphur Bay, 

 I. Clarion, no. 39-14, 16 Mar. 1939. 



