NO. 10 DAWSON : MARINE ALGAE, GULF OF CALIFORNIA 205 



parenchymatous disk, with only a few peripheral short free filaments. In 

 E. Polysiphoniae there is no indication of a central parenchymatous disk. 

 The filaments are all free, more or less crooked and distorted, and the 

 branching is alternate or at times secund, usually arising from the center 

 of the cells. Between these two extremes we have E. codicola with a slight 

 central disk, E. mexicana and E. cingens. In all cases the reproductive 

 cells are merely vegetative cells enlarged and more or less metamorphosed. 

 In E. Polysiphoniae those of the central part of the thallus are enlarged to 

 almost spherical, whereas those near the margin may only be slightly 

 swollen. This condition does not seem to be the case in the other species." 



Entocladia Polysiphoniae S. & G. 



Setch. & Card., 1924, p. 718, pi. 13, fig. 18. 



Growing in the membrane of Polysiphonia Marchantae, Bryant 7, La 

 Paz ; M. 50b, Guaymas Bay, May. Not again detected. 



Entocladia mexicana S. & G. 



Setch. & Gard., 1924, p. 719, pi. 19, fig. 57. 



Growing within the membrane of Chaetomorpha antennina, J. 49b, 

 La Paz; within the membrane of Valoniopsis Hancockii, D. 215, Puerto 

 Refugio, Jan. 



Genus PRINGSHEIMIA Reinke 

 Pringsheimia Marchantae S. & G. 



Setch. & Gard., 1924, p. 720, pi. 12, fig. 8. 



Growing on various species of Laurencia, M. 68, La Paz, May. Not 

 again detected. 



Family Valoniaceae 



Genus DIGTYOSPHAERIA Decaisne 



Dictyosphaeria Versluysii W.-v. B. 



Weber-van Bosse, 1913, p. 64, pi. II, fig. 6. 



Specimens from the tropical waters of the southern Gulf agree very 

 well with the figure and description given by Madame Weber of this spe- 

 cies. The plants grow attached to coral heads in shallow lagoons, are 

 solid in structure throughout, and are made up of very large cells 1.2 to 

 1.8 mm. in diameter. Unfortunately, specimens were not preserved in 



