NO. 2 DAWSON: MARINE RED ALGAE OF PACIFIC MEXICO 247 



irregularly and proliferously pinnate from the margins, 450-800 /x thick, 

 all flattened blade-parts at maturity developing numerous short, gigarti- 

 noid, spinose papillations over all surfaces and margins; texture lubric- 

 ous vv^hen fresh, drying to rough coriaceous; cortex 8-10 cells thick, the 

 outer 4-5 cells very small, pigmented and forming regular anticlinal 

 filaments; medulla of a loose network of slender, branched filaments 

 2.5-3.0 [X in diameter; tetrasporangia not in sori, embedded in the cortex 

 just below the surface of all upper thallus parts, 32-40 /x long, 9-14 ju, 

 wide, causing some nemathecial modification of cortical filaments ; carpo- 

 gonial branches 2-celled ; gonimoblast development apparently as in G. 

 filicina; cystocarps scattered over the blades, appearing as minute warts 

 on the surface of dried plants among the larger spinose papillae ; anther- 

 idia borne in a continuous superficial layer over entire blade, causing 

 some nemathecial modification of outermost cortex. 



Type: Holotype is Johnston 113, April 1921, on sheet 1370 in the 

 Herbarium of the California Academy of Sciences, San Francisco, Cali- 

 fornia. 



Type locality: Isla San Esteban, Gulf of California, Mexico. 



Mexican distribution: Pacific Baja Calif. — D. 8356, Isla 

 Guadalupe, Dec; D. 9770 (?), Isla Cedros, Apr.; D. 9075, Islas San 

 Benito, Apr.; D. 1622, near Punta Maria, Apr.; D. 9206 (?), Bahia 

 Asuncion, Apr.; D. 9459 (0), Punta Abreojos, Apr. Gulf of Calif. — 

 D. 696, Puerto Libertad, Feb.; D. 769, Isla Patos, Feb.; D. 1062, Isla 

 Alcatraz, Feb.; D. 91-40, Isla Tiburon, Jan.; Johnston 113, Isla San 

 Esteban, Apr.; D. 568, Feb., D. 1826, D. 1834 (0), D. 1835 (d), 

 D. 1860 (?), D. 1907 (?), D. 1938 (?), D. 1939 (?), May, D. 3516, 

 Nov., Ensenada de San Francisco, near Guaymas; D. 1655, Bahia Car- 

 rizal, near Cabo Arco, May; D. 537-538 (juvenile), Feb., D. 1804, 

 May, Punta Colorado, near Guaymas. Sinaloa — D. 10836 (depauperate 

 9), Mazatlan, June. 



The illustration of the type specimens (Setchell and Gardner 1924, 

 pi. 83) shows only the broad fronds oi mature plants with unusually 

 simple blades. As a rule, the plants are much more abundantly branched, 

 mainly pinnately, and the marginal and surface papillations may be in- 

 determinate to the extent of causing the frond to appear proliferous. A 

 very lubricous texture is characteristic of the species and distinguishes it 

 readily in the field from superficially similar specimens of Gigartina (as 

 G. armata at Isla Cedros). Juvenile specimens are only slightly papillate 

 and show a usually abundant branching of the several suberect blades 

 arising from a common discoid holdfast. 



