NO. 10 DAWSON : MARINE ALGAE, GULF OF CALIFORNIA 331 



Polysiphonia simplex Hollenberg 



Hollenberg, 1942, pp. 782-783, fig. 18. 



Plants saxicolous, forming dense mats often of considerable extent, 

 with creeping, tangled basal filaments 250-360 fi diam., of segments 

 mostly less than one diameter long, attached by unicellular rhizoids with 

 lobed tips which are cut off by a curving wall from the proximal end of 

 the pericentral cells; prostrate filaments giving rise in an exogenous, 

 assurgent manner to erect branches l-3-(7) cm. high and 160-250 /t 

 diam., with main axes distinct and sparingly branched ; branches exoge- 

 nous, arising on all sides; trichoblasts 1-3 times forked, one per segment, 

 arising in a left-hand spiral with a i/4 divergence, soon deciduous, leaving 

 persistent scar-cells; branches replacing trichoblasts, not arising in con- 

 nection with them; first trichoblast on branch arising (l)-3-4 segments 

 from the branch-base; tetrasporangia to 70 p. diam., spirally arranged in 

 the somewhat bulging branch tips; cystocarps ovoid, sessile, 300-350 jx 

 diam. ; antheridial branches arising from one fork of a trichoblast, meas- 

 uring 100-170 by 35-40 /x, without a sterile tip; plants medium to dark 

 brown, drying nearly black, growing in the middle to upper littoral zones. 



Type: from Laguna Beach, Orange County, California. 



Several Gulf of California plants are tentatively to be placed here, 

 though the segments are much shorter than those in typical southern 

 California specimens. 



D. 124, Turner's Island, Jan.; D. 312, Gonzaga Bay, D. 402, Pond 

 Island, Feb.; D. 475k, from 30-36 meters, Ensenada de San Francisco, 

 near Guaymas, Feb.; D. 540b, Agua Verde Bay, Feb.; D. 652, rocky 

 point near Kino, July; D. 697, 724, Turner's Island, July. 



Polysiphonia Hancockii sp. nov. 

 Plate 50, Fig. 2 



Frondes usque ad 1 cm. altae, axibus 1-paucis e disco basali parvo, in parte 

 rhizinarum corticarum e basi axis crassae orientium emergentibus ; axi primaria 

 percurrente, inferne in partibus usque ad tota corticata, erecta, rigida, basim 500 

 \i crassa, ramos multos laterales in incremento limitatos praebente et iis aspectura 

 excurrente arborescentem donatantibus. 



Plants to 1 cm. high, 1 -several axes from a small, discoid holdfast, 

 partly formed of cortical rhizoids arising from the base of the thick axis ; 

 no prostrate portions present ; main axis percurrent, partly to fully corti- 

 cated in lower parts, erect, rigid, stout, trunklike, 500 jx. thick at base, 



