274 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 17 



by a disc, simple or branched, a thickened midrib-like area often extend- 

 ing from the stipe into the base of the blade ; thickness variable in plants 

 of different depths and habitats, from 50 ju, to 220 (280) /i, mainly 

 dependent upon the length of the transverse medullary filaments ; outer 

 cortical cells in surface view angular, separated by thick walls, 7 jit or 

 more in greater diameter; transection showing an outer cortex commonly 

 of a single layer of cells, but often with a dz incomplete or less compact 

 second layer ; subcortex usually of a single irregular, loose layer of larger, 

 more or less arachnoid cells arranged periclinally and giving rise to 

 anticlinal medullary filaments of 1-3 cells which extend from subcortex 

 to subcortex, these filaments variable in length in different plants; 

 medulla with some periclinal filaments running irregularly through it, 

 of which the larger commonly have highly refractive contents and ex- 

 hibit prominent arachnoid or stellate "ganglia" ; gonimoblast developing 

 from an auxiliary cell in a separate system from that bearing the carpo- 

 gonial branch; gonimoblast pedicellate on the prominent auxiliary cell; 

 cystocarps completely embedded, inconspicuously ostiolate, scattered, 

 100-180 ju. in diameter; carpospores in a compact, subspherical mass, 

 small, angular, 9-12 /i in greatest diameter; antheridia superficial, de- 

 veloping in a network pattern by progressive angular division and modi- 

 fication of outer cortical cells; tetrasporangia scattered through the un- 

 modified cortex, cruciate, ovate to subspherical, 11-14 ju. in diameter. 



Type: Holotype is Vives 20d, Feb. 28, 1911, in the Herbarium of 

 the New York Botanical Garden, New York. A portion of the holotype 

 specimen is on sheet 649499 in the Herbarium of the University of 

 California Berkeley. 



Type locality: Near La Paz, Baja California, Mexico. 



Mexican distribution : Gulf of Calif. — D. 347-40, 30 m., Punta 

 Penasco, Feb.; D. 182-40, 24-44 m., Puerto Refugio, Isla Angel de la 

 Guarda, Jan.; D. 138-40, 4-32 m., Isla Tiburon, Jan.; D. 888, Bahia 

 de Agua Dulce, Isla Tiburon, drift, Feb.; D. 1942, drift, May, D. 

 7216, 8-20 m., Mar., D. 10975-10976, drift, June, Ensenada San Fran- 

 cisco; D. 6964, 6980-6982, 4-30 m., Bahia Salinas, Isla Carmen, Mar.; 

 D. 6904b, 6920, 6927, 8-20 m.. Canal de San Lorenzo, Mar. ; D. 6839, 

 20 m., D. 6867, 40 m., D. 6879, 55 m., Bahia San Lucas, Mar. Archip. 

 de Revillagigedo — Taylor 39-38a, 56-102 m., near Isla Clarion, Mar.; 

 Taylor 34-14, 24-32 m., Bahia Braithwaite, Isla Socorro, Jan.; Taylor 

 39-66, 41-84 m., Isla Socorro, Mar. 



This appears to be a rather common and variable species of the 

 deeper sublittoral waters of the Gulf of California area and southward. 

 It varies considerably in thickness, and hence in the appearance of the 



