NO. 1 DAWSON : MARINE RED ALGAE OF PACIFIC MEXICO 29 



Acrochaetlum paclficum Kylin 



Kylin, 1925, p. 11, figs. 4g-I; Doty, 1947, p. 162. Rhodochorton 

 pacificum (Kylin) Drew, 1928, p. 169, pi. 38, fig. 25. 



Thalli epiphytic, less than 1 mm. high, consisting of erect filaments 

 arising from non-confiuent, radiating filaments on the surface of the 

 host; erect filaments 4.0-6.0 ix in diameter, with cells 2-4 times as long 

 as broad, with few long branches and numerous short, secund branchlets 

 of 1-3 cells; chromatophores parietal, with a large pyrenoid in the distal 

 part; reproduction by monosporangia borne terminally and laterally on 

 the secund branchlets, ellipsoidal, mostly 8.5-9.5 ju. long. 



Type: Holotype or specific syntypes not designated, but Kylin's 

 original collections are probably in his private herbarium at the Univer- 

 sity of Lund, Sweden. 



Type locality: Vicinity of Friday Harbor, Washington (several 

 localities indicated with the original description). 



Mexican distribution: Gulf of Calif. — D. 7230, on Scinaia 

 latifrons, Ensenada de San Francisco, Sonora, March. These specimens 

 are in close agreement with the species as known heretofore from the 

 northern Pacific Coast of the United States, but differ in at least one 

 respect. Whereas Kylin described his Puget Sound plants as having a 

 "unistratose basal disc, consisting of more or less coherent creeping fila- 

 ments," the present material seems to have quite non-confluent basal 

 filaments which branch and radiate without particularly close contact. 



Acrochaetium variabile (Drew) G. M. Smith 



Smith, 1944, p. 179; Dawson, 1949, p. 222. Rhodochorton variabile 

 Drew, 1928, p. 174, pi. 38, fig. 28, pi. 39, figs. 30-31. 



Thalli epiphytic, 0.6-1.0 mm. high or more, consisting of a basal 

 stratum of creeping filaments forming a layer 1-2 cells thick from which 

 arise numerous erect filaments; erect filaments straight, 8.0-9.5 fi in 

 diameter, with or without long branches below, but in either case pro- 

 vided above with secund series of short branchlets which may in turn be 

 branched; cells 2-3 (4) times as long as wide, with a parietal chromato- 

 phore and a single large pyrenoid ; reproduction by monospores ; mono- 

 sporangia terminal or lateral on the short, secund branchlets, ovoid, 5-7 

 ju. broad. 



Type: Holotype is Gardner 4659, Dec. 1920, on sheet 266281 in 

 the Herbarium of the University of California, Berkeley. 



