50 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 17 



Agua Verde, Mar.; D. 3100b, 5 km. north of Cabo Pulmo, Nov.; D. 

 3217, Punta Palmilla, Nov.; D. 3328, Cabeza Ballena, Nov. 



As Chou suggested in 1945 in discussing specimens from Costa Rica 

 identified as Galaxaura stupicaulis Kjellm., the characters separating 

 that species from G. arborea appear unnatural and inconstant. In my 

 Cabeza Ballena specimens one part of a frond may show the proliferous 

 branches of G. stupicaulis with their basal tufts of extended assimilatory 

 filaments, while other parts of the same thallus may have the entirely 

 continuous, smooth branches of G. arborea. 



In the Galaxaura collections from Costa Rica which she studied, 

 Chou found asexual plants corresponding with G. stupicaulis (G. arborea 

 of this account) mixed with sexual plants which she classified as G. 

 veprecula. In some of the Mexican collections the same situation occurs 

 and strengthens the suggestion that G. arborea and G. veprecula may be 

 the two phases of one natural species. 



Galaxaura fastigiata Decaisne 

 Plate 20, fig. 2 



Decaisne, 1842, p. 116; Dawson, 1944, p. 258; Svedelius, 1945, p, 

 28, text figs. 14-16, pis. IV, V, VI fig. 2. Galaxaura oblongata (Ellis k 

 Sol.) Lamx., as interpreted by Chou, 1947, p. 7, and by Taylor, 1945, p. 

 142, at least as regards the Mexican material. 



Thallus saxicolous, 4-6 cm. high, attached by a small, discoid hold- 

 fast, abundantly dichotomously branched to form a clump ; segments 

 cylindrical, pinkish in color, 0.8-1.3 mm. in diameter, stiff, entirely glabr- 

 ous, slightly annulate or transversely striate, heavily calcified, but only in 

 the cortical zone, none of the calcification extending into the medullary 

 zone or over the epidermal layer; cortical zone consisting of four layers, 

 the outermost epidermis of small flat cells, the inner three layers of suc- 

 cessively larger rotund cells; calcification usually fractured at the nodes, 

 permitting the branches to lie in a more or less fastigiate manner, the 

 confinement of the heavy calcification to the cortex causing the internodes 

 to have the appearance of tubes ; reproduction sexual. 



Type: Holotype not designated. A syntype, Cumming Exsicc. 

 2241, is in the Herbarium of the Riksmuseum, Stockholm, Sweden. 



Type locality: Not specifically designated, but the Cumming 

 syntype is from Manila, Philippine Islands. 



Mexican distribution : Pacific Baja Calif. — D. 8484, Isia Gua- 

 dalupe, Dec; D, 9950, 10 miles west of Punta Malarrimo, Bahia Viz- 



