NO. 1 DAWSON : MARINE RED ALGAE OF PACIFIC MEXICO 47 



monoecious as Setchell supposed all species of Scinaia to be. It is to be 

 noted that antheridial plants of another dioecious species, S. articulata 

 Setch., are shown by Dawson (1949a, pi. 7, figs. 44-45) as having a 

 continuous, cap-like sorus. The antheridial characters and the monoecious 

 or dioecious condition must be rechecked in all the species studied by 

 Setchell for, as Svedelius (1915) has pointed out, Setchell did not 

 recognize the difference between antheridia and monosporangia. 



Scinaia latifrons seems to be identical in habit and in general struc- 

 ture with the plant described as S. cottonii from Japan. Okamura ( 1921 ) 

 has already suggested that the two may be identical and has pointed out 

 how Japanese specimens have the same transverse wrinkles as are indi- 

 cated by Howe's illustration of the Mexican type. Recent Mexican 

 collections show that this transversely wrinkled condition may often 

 occur, but not always. In size, anatomy, and in position of the cystocarps, 

 as shown by Okamura's illustration, S. cottonii agrees with S. latifrons. 

 Antheridia are, however, reported by Setchell in the Japanese plant as 

 "in small clusters, scattered" and by implication, borne on monoecious 

 plants. In view of the current discovery of marginal antheridial sori in 

 S. latifrons, and of Setchell's failure to distinguish between monospor- 

 angia and antheridia in his work, the male situation in S. cottonii must 

 be reinvestigated despite Setchell's illustration (1914, pi. 2, fig. 24) 

 which appears to show antheridia rather than monospores. If the antheri- 

 dia in S. cottonii are indeed as they were originally described it will 

 furnish a ready criterion for distinguishing these otherwise similar plants. 



Scinaia minima Dawson 



Dawson, 1945a, p. 103, pi. 20, fig. 1. 



Thalli saxicolous, 2-4 cm. high from a small discoid holdfast, cylind- 

 rical, 1.5-2.5 mm. in diameter, tapering to a slender base, 3-4 times 

 dichotomously branched, smooth, unconstricted, with narrow axils; 

 epidermis of large, colorless utricles 20-23 ja high, 15-18 j-i in diameter; 

 hypodermis of a single layer of closely set small cells, 10-12 /x, in dia- 

 meter; cystocarps scattered irregularly over the frond, immersed, 200- 

 275 jx in diameter, with a thin periderm of about 2 layers of cells. 



Type: Holotype is a collection by K. O. Emery, May 1945, in the 

 Herbarium of the University of California, Berkeley. An isotype is on 

 sheet 8910 in HAHF. 



Type locality: Dredged from a depth of 25-30 meters in Kel- 

 lett Channel, between Isla Cedros and Punta San Eugenio, Baja Cali- 

 fornia, Mexico. 



