200 University of California Pnhlications in Botanjj [Vol.8 



3. Filaments not over 40^ in diameter 1. C. californica (p. 200) 



3. Filaments over 40yu in diameter 2. C. aerea (p. 200) 



4. Basal cell short, not over 3 mm. long 3. C. melagonium (p. 201) 



4. Basal cell longer, up to 9 mm. long 4. C. antennina (p. 203) 



5. Filaments 45-loO/n (or even 200ai) in diameter 5. C. cannabina (p. 204) 



5. Filaments over 500/i in maximum diameter 6. C. torta (p. 205) 



1. Chaetomorpha californica Collins 



Filaments attached b}^ a small disk formed of short, stout, 

 coaleseent rhizoids, erect, straight or flexuous, of uniform diameter 

 throughout, not contracted at the nodes, about 20 cm. long, 20-40/x 

 diam. ; segments 1-2 times, rarely 3-4 times, as long as the diameter. 



Growing on sandstone in shallow pools along high-tide level. 

 Observed at Laguna Beach and at La Jolla, southern California. 



Collins, in Collins, Holden and Setchell, Phyc. Bor.-Amer. 

 (Exsicc), 1900, no. 664; New species, etc., Rhodora, vol. 8, 1906, 

 p. 106, Green Alg. N. A., 1909, p. 325. 



Collins (1909, p. 326) says of this species that it is "the most 

 slender erect marine species known" and that it is "not likely to be 

 mistaken for any other." He has, however, recently described a still 

 more slender species (C minima) from Bermuda. In habit and 

 habitat, C. californica resembles Chaetomorpha aerea as generally 

 understood, but is much more slender than that species. The basal 

 segment is very suddenly narrowed at the base and is up to 200ju. long. 

 The base, itself, is provided with a number of thick, short, very slightly 

 if at all branched, stout rhizoids whose outer walls coalesce to form a 

 sort of disk. 



2. Chaetomorpha aerea (Dillw.) Kuetz. 



Plate 14, figs. 9-11 



Filaments rigid, erect, dark green becoming yellowish with age, 

 nearly cylindrical throughout except at the tapering base, attached 

 by delicate rhizoids issuing from the lower end of the basal segment 

 and later coaleseent into a more or less solid disk, 125-300/x diam. ; 

 segments at first cylindrical, later varying to almost spherical in the 

 fertile segments, 0.5-2 times as long, basal segments much longer; 

 membrane hyaline, thick, at times lamellate ; chromatophore at first 

 continuous, finely fenestrate. 



Growing in rock pools along high-tide limit or even above. Com- 

 mon on the coast of California from Monterey to San Diego. 



