NO. 1 DAWSON : MARINE RED ALGAE OF PACIFIC MEXICO 75 



complanate, giving rise to about 3 orders of irregularly alternate or sub- 

 opposite, distichous lateral branchlets, the first 1-2 orders of long, in- 

 determinate branches, but the ultimate and subultimate orders relatively 

 short and often more or less uniform in length, giving a non-congested 

 aspect; successive branch-orders reduced slightly in diameter; ultimate 

 branchlets not markedly geniculate ; transection showing a medulla of 

 rather irregular sized cells up to 18 /a in diameter, the rhizoidal fila- 

 ments strictly longitudinal, in a dense subcortical zone with only a few 

 scattered in the medulla; cystocarps (not seen in Mexican material) 

 usually solitary in the center of a short, acute branchlet, these not 

 branched or much prolonged above and usually not producing additional 

 fertile branchlets below; tetrasporangia in terminal sori in short, blunt, 

 usually simple or lobed ultimate ramuli; antheridia (not seen in Mex- 

 ican material) in longer ramuli which are quite variable in diameter in 

 different parts. 



Type: Holotj^pe is Gardner 2569 on sheet 295841 in the Her- 

 barium of the University of California, Berkeley. 



Type locality: Laguna Beach, Orange County, California. 



Mexican distribution : Pacific Baja Calif. — D. 263, 8 km. south 

 of Punta Descanso, Jan. (tetrasporic) ; D. 1239 (Apr.), 8648 (Dec), 

 Socorro (tetrasporic) ; D. 8820, Punta Baja, Jan. (tetrasporic) ; D. 

 8700, shore at Canada Quemado, Jan. (tetrasporic). 



This species seems distinct from Gelidium purpurascens on the one 

 hand by its more slender proportions and by its solitary cystocarps, and 

 from G. papenfussii on the other by its usually shorter, more uniform 

 ultimate and subultimate branches and short, usually simple (or lobed) 

 tetrasporangial branchlets. 



Gelidium ? sonorense sp. nov. 

 Plate 5, fig. 5 ; Plate 21, fig. 2 



Thallis 4-6 cm. altis, in fascibus laxis ; partibus erectis planis, anguste 

 ligulatis, 180-230 /^ crassis, 900-1100 /A^latis, aperte pinnateque ramosis 

 intervallis valde irregularibus ; ramis 2-3 ordinum, in omnibus ordinibus 

 fere eiusdem latitudinis ; filamentis rhizoideis abundantibus per medullam 

 subcorticemque ; tetrasporangiis in soris anguste elongatis in ramis ordi- 

 num superiorum, ope marginum prominentium, sterilium limbatis. 



Thalli saxicolous, loosely clumping, 4-6 cm. high, consisting of several 

 semi-erect or spreading stipitate fronds arising from a few short, creep- 

 ing, stoloniferous branches attached by several small discs or pegs ; erect 



