NO. 1 DAWSON : MARINE RED ALGAE OF PACIFIC MEXICO 27 



Type: Holotype is AHF Sta. 976-39, May 27, 1939 on sheet 

 26803, including vial 826, in HAHF. 



Type locality: Epiphytic on Scinaia articulata dredged from a 

 white sand bottom at a depth of 30-40 m. north of Santa Barbara Island, 

 California (33° 31' N., 119° 01' 50'' W.). 



Mexican distribution: Gulf of Calif. — D. 661a, on Scinaia 

 johnstonae, Puerto Libertad, Feb.; D. 700a, on Gloiophloea confusa, 

 Puerto Libertad, Feb.; D. 7197a, on Scinaia latifronSj Ensenada de San 

 Francisco, Mar.; D. 6885a, on Scinaia latifrons, Punta Frailes, Mar. 

 This species is probably to be expected throughout the range of Scinaia 

 and Gloiophloea in Mexico, for it has also been detected on Gloiophloea 

 from the Galapagos Archipelago. 



Acrochaetium amphiroae (Drew) Papenfuss 



Papenfuss, 1945, p. 312; Dawson, 1945b, p. 60; Doty, 1947, p. 162. 

 Rhodochorton a?nphiroae Drew, 1923, p. 179, pi. 40, figs. 34-37; Smith, 

 1944, p. 183, pi. 40, figs. 5-7. 



Thalli 1-2 mm. high, growing in the genicula of articulated coral- 

 lines, attached by a basal mass of entangled filaments growing over the 

 surface and in part penetrating and becoming endophytic within the 

 genicula of the host; erect filaments verj'^ irregularly, but more or less 

 unilaterally branched, the branchlets often in turn branched on the ad- 

 axial side; cells cylindrical, 12.0-14.0 /x in diameter, 1.5-3 times as long 

 as broad ; chromatophore parietal, with one pyrenoid embedded in it usu- 

 ally toward the apical end of the cell ; monosporangia terminal and 

 lateral on the branchlets, sometimes so abundant as to form dense clus- 

 ters, ovoid, 10-13 ju, by 16-19.5 ju.; chromatophore of the sporangium 

 apical, with one pyrenoid. 



Type: Holotype is Gardner 1928 on sheet 276411 in the Herbar- 

 ium of the University of California, Berkeley. An isotype is on sheet 

 8792 in HAHF. 



Type locality: Whites Point, San Pedro, California. 



Mexican distribution: Pacific Baja Calif. — D. 35-45, (in Herb. 

 U. C.) on Bossea, 3 km. south of Cabo Colnett, Apr.; D. 9859a, on 

 Bossea, South Bay, Isla Cedros, Apr. 



Acrochaetium plumosum (Drew) G. M. Smith 



Smith, 1944, p. 180; Dawson, 1945b, p. 65; Dawson, 1949, p. 219. 

 Rhodochorton plumosum Drew, 1928, p. 173, pi. 39, fig. 29. 



