NO. 1 DAWSON : MARINE RED ALGAE OF PACIFIC MEXICO 83 



Type: Holotype is Forsskal's original specimen (illustrated by 

 Bc^rgesen) under number 874 in the Botanical Museum of the Univer- 

 sity of Copenhagen, Denmark. 



Type locality: "Ad Mochhae littora" on the Red Sea. 



Mexican distribution: Gulf of Calif.— D. 594-40, 610-40, Isla 

 Espiritu Santo, Feb.; D. 633-40, Bahia San Jose del Cabo, Feb.; D. 

 3249, Punta Palmilla, Nov.; D. 3322, (Nov.), D. 6780, (Mar.), 

 Cabeza Ballena. Guerrero — D 3836, Acapulco, Feb. (mature tetra- 

 sporic). 



Gelidiella hancockii Dav^^son 



Plate 12, figs. 6-7 



Dawson, 1944, p. 261, pi. 43, figs. 1-2. Gelidiella mexicana Dawson, 

 1944, p. 262, pi. 43, fig. 3, except Guaymas specimens. 



Thalli saxicolous, tufted, 4-8 mm. high, cylindrical throughout, 120- 

 200 /x in diameter, consisting of spreading, creeping, prostrate parts 

 attached along their under surfaces by numerous rhizoids, giving rise to 

 congested, irregularly, but rather sparsely polystichously branched erect 

 parts; apices acute but not attenuate, with a distinguishable apical cell; 

 internal structure consisting of a central medullary core of elongated 

 cells 7-8 ju, in diameter grading into the cortex of somewhat smaller, 

 isodiametrical cells ; rhizoidal filaments absent ; tetrasporangia irregular- 

 ly arranged in slightly swollen, short branchlets of branch-tips. 



Type: The holotype designated as Dawson 651-40, July 16, 1940, 

 on sheet 18 in HAHF is apparently lost. The type sheet contains only 

 material of the paratype collection, Dawson 288-40. 



Type locality: Rocky point just north of Kino, Sonora. 



Mexican distribution: Gulf of Calif, — D. 288-40, Puerto Re- 

 fugio, Isla Angel de la Guarda, Jan. ; D. 401a-40, Isla Pond, Isla Angel 

 de la Guarda, Feb. ; D. 328a-40, Bahia Gonzaga, Jan, 



The sterile material described as Gelidiella mexicana, though some- 

 what more slender, seems upon reexamination to approach G. hancockii 

 too closely to be separated. Accordingly, the former name is reduced 

 under G. hancockii which has page priority. 



This species resembles a small, tufted form of Gelidium crinale or 

 Wurdernannia niiniata. In fact, specimens from Guaymas (Drouet & 

 Richards 3227) tentatively referred to G. mexicana have proved to be de- 

 pauperate G. crinale. From G. crinale it differs in the absence of rhizoid- 

 al filaments ; from Wurdernannia it differs in its acute apices with a dis- 

 tinct apical cell. 



