122 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 17 



or flattened throughout, 130-160 /x, wide below, mostly 2-2.5 diameters 

 long, smaller above, 70-100 ix wide but of the same proportions; tetra- 

 sporangial conceptacles urn-shaped, slightly compressed, about 300 /i 

 wide, rostrate, with a simple or forked antenna-like branch from either 

 shoulder; antheridial conceptacles cjdindrical, ellipsoid, 150 ju, in dia- 

 meter, about 300 fi long, terminal, non-antenniferous ; carposporangial 

 conceptacles not seen. 



Type: Holotype is Crocker 19, Feb. 2, 1938, in the Herbarium of 

 the California Academy of Sciences, San Francisco, California. An 

 isotype is on sheet 54868 in HAHF. 



Type locality: Epiphytic on old Padina, Bahia Piedra Blanca, 

 Costa Rica. 



Mexican distribution: A collection is at hand (D. 10075) 

 from 11 miles west of Punta Malarrimo, Bahia Vizcaino, Baja Calif., 

 which consists of one juvenile and one adult plant on an old Gracilaria 

 fragment. It shows close correspondence with the type although not all 

 of the axes have such markedly compressed segments. 



Jania tenella var. zacae is apparently similar to the Japanese /. 

 radiata Yendo which also has flat segments, but to judge from Yendo's 

 meager description of sterile material, our plants are smaller and have 

 segments about half the size of those of the Japanese plant. 



Key to the Mexican Species of Corallina 



1. Intergenicula cylindrical throughout or only slightly compressed 2 

 1. Intergenicula prominently compressed or flattened at least above 



and in main axes 3 



2. Thalli small, less than 2 cm. high, pinnate-distichously and 



dichotomously branched C janioides 



2. Thalli to 3.5 cm. high, polystichously or verticillately 

 branched from percurrent main axes . . C. polysticha 

 3. Conceptacles normally all terminal, rarely congested ... 5 

 3.. Conceptacles normally both terminal and lateral from flattened 



faces of intergenicula, often congested 4 



4. Ultimate intergenicula simple, lanceolate or spatulate, some- 

 times somewhat lobed . C. pinnatif olia var. pinnatifolia 

 4, Ultimate intergenicula pinnate, palmate or flabellate, promi- 

 nently digitately lobed . . C. pinnatifolia var. digitata 

 5. Tetrasporic conceptacles normally antenniferous, at least pre- 

 dominately so 6 



