74 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 17 



tate base to 1.0-1.5 mm. broad, repeatedly distichously branched, the 

 branches mostly opposite, but in part alternate ; ultimate pinnate branch- 

 lets appearing regular and of quite uniform size, 1-2 mm. long and less 

 than 0.5 mm. broad ; transection of younger parts showing numerous 

 rhizoidal filaments confined mainly to the subcortical zone, but in older 

 parts the medulla more or less densely packed with rhizoidal filaments, 

 some of them somewhat interlaced ; tetrasporangia formed in elongated 

 sori in somewhat expanded distal parts of ultimate branchlets ; cysto- 

 carps abundant, about 550 ju, broad, solitary in distal part of each pin- 

 nule; antheridia unknown. 



Type: Holotype is Johnston 27, June 1921, No. 1343 in the 

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

 fornia. An isotype is on sheet 69, including slides 210, 1072-1074, in 

 HAHF. 



Type locality: Bahia San Francisquito, Baja California. 



Mexican distribution: Pacific Baja Calif. — D. 1451, Punta 

 Santa Rosalia, Apr. (sterile) ; D. 6720 (Mar.), D. 9299 (May), Punta 

 Entrada, Isla Magdalena; Osorio-Tafall, May 1944, dredged in 6-8 

 m., Man of War Cove, Bahia Magdalena. Gulf of Calif. — The most 

 abundant of the larger gelidia, found at most rocky shore stations be- 

 tween Bahia Tepoca on the north and Bahia Agua Verde on the south. 



Although more than 225 mature reproductive specimens from some 

 20 stations have been examined, no antheridial plants have been detected. 

 The ratio of cystocarpic to tetrasporic plants is about one to two. The 

 abundance of cystocarps is rather unusual, too, for a single plant bears 

 one on each of many hundreds of ultimate pinnules. 



A striking anatomical feature is the usual abundance of rhizoidal 

 filaments in the medulla, although in young parts and in mature parts of 

 some examples they are confined mainly to the subcortex as in most other 

 species of Gelidium. 



The more or less uniform length of the ultimate pinnules gives this 

 species a characteristic regularity of branching which distinguishes it 

 from others in the Mexican flora. 



Gelidium pulchrum Gardner 

 Plate 5, fig. 2 



Gardner, 1927a, p. 279, pi. 50-53; Doty, 1947, p. 163; Dawson, 

 1949, p. 222. 



Thalli saxicolous, 7-23 cm. high, consisting of several to many erect 

 fronds from a holdfast of branched stolons attached by small discs ; pri- 

 mary branches about 500-600 (to 750) }i in diameter, compressed to 



