NO. 10 DAWSON : MARINE ALGAE, GULF OF CALIFORNIA 223 



On rocks with crustaceous corallines, lower littoral : D. 397a, Tepoca 

 Bay, Feb.; D. 468, San Esteban Island, Feb.; D. 757a, Turner's Island, 

 July; D. 318a, Gonzaga Bay, Jan. 



Ralfsia californica S. & G. 



Setch. & Gard., 1925, p. 497, pi. 36, fig. 22. 



Unfortunately, the material is sterile, but it is a thin species which 

 seems to correspond in most respects with R. californica. Fertile material 

 will be required to establish this determination. 



D. 619, on rocks with crustaceous corallines in quiet water of shal- 

 low lagoons, San Gabriel Bay, Espiritu Santo Island, Feb.; D. 479c, 

 Puerto San Carlos, near Guaymas, Feb.; D. 130a, reef at Turner's 

 Island, Jan. 



Ralfsia Hancockii sp. nov. 

 Plate 31, Figs. 6,7; Plate 54, Fig. 2 



Frondes leves, crustosae, irregulariter lateque lobatae, usque ad 6 cm. diam. 

 prorsum per rhizinas pluricellulares ad substratum arete adhaerentes, in partibus 

 sterilibus 175-200 \i crassae; cellulis stratorum 2-3 basalium horizontaJiter elon- 

 gatis et iis ramos assurgentes ad directionem marginium producentibus; partibus 

 fertilibus 150-175 \i crassis, inferne hypothallo 3 stratoso compacto cellulis cubicis 

 et superne paraphysibus gracilibus et sporangiis unilocularibus compositis; para- 

 physibus 150-175 n longis, gracilibus, clavatis, 7-9 \i diam., sporangiis uniloculari- 

 bus 90-110 n longis, 20-30 n diam. 



Thallus flat, smooth, crustose, irregularly and broadly lobed, to 6 cm. 

 in diameter, bister brown, firmly adhering to the smooth rock substratum 

 throughout, largely by means of small, branched, pluricellular rhizoids; 

 sterile vegetative portions 175-200 fx thick; cells of basalmost 2-3 layers 

 elongated horizontally, these leading into branching, assurgent rows in 

 the direction of the margins, the cells averaging about 12 by 25 /x in di- 

 mensions; fertile portion 150-175 fx thick, of slender paraphyses and uni- 

 locular sporangia from a compact, 3-tiered hyperthallic layer of quadrate 

 cells; paraphyses 150-175 /x long, slender, clavate, 7-9 /a diam. at thickest 

 outer ends, of cells much longer than broad below, mostly at least 1.5 

 times as long as broad above; unilocular sporangia clavate, with a nar- 

 row basal stalk, 90-1 10 yu, long, 20-30 ju. in diameter. 



Type : D. 640, growing over bare rock surfaces in middle littoral, 

 San Jose del Cabo, Feb. 16, 1940. Herb. AHF no. 9. 



This species is very distinct among those of our region in its light 

 brown color, its thick, adherent thallus of assurgent cell rows, and in the 

 length and slender proportions of the paraphyses. 



