1925] SetcheU-Gardner: Melanophyceae 541 



The f. expansa is a variation of the typical form in which the frond 

 is more ample, less regular in shape, usually creeping over filamentous 

 algae and forming secondary attachments. It has a smooth surface 

 in the sense of not being tuberculate or conspicuously lobed. It is 

 somewhat thicker than the typical form, with the clusters of hairs 

 sunk in tissues. The layers of colorless cells are greater in number 

 than in the typical form (usually 5 to 7). 



3. Colpomenia sinuosa f. expansissima S. and G. 



Fronds 3-6 dm. diam., thin, sinuose, with minute, spine-like pro- 

 jections. 



Floating in billowy masses in San Francisquito Bay, Lower Cali- 

 fornia. 



Setchell and Gardner, Mar. Alg. Gulf of Calif., 1924, p. 726. 



This form is probably an extreme of f. expansa, but it has only 

 been found floating. It is thinner and less even in outline and surface, 

 but is similar in every other way. The only specimens are sterile and 

 show no hairs. 



4. Colpomenia sinuosa f. tuberculata (Saunders) S. and G. 



Fronds sessile, hollow, rigid and somewhat coriaceous, very irregu- 

 lar in shape and size, usually somewhat flattened, 5-10 cm. diam., 1-2 

 mm. thick ; surface much convoluted, wrinkled and folded, at maturity 

 covered w-ith blunt warts or tubercules ; color dark brown ; cortex of 

 3-5 rows of cuboidal cells, the inner layer of 5-8 rows of large, 

 irregular, thin-walled cells; plurilocular gametangia 20-25/a long, 

 3-4/a wide ; paraphyses 22/a long, 5/a wide. 



Growing on rocks and on other algae, often aggregated in large, 

 brain-like masses, in the middle of the littoral belt. From Unalaska, 

 Alaska, to La Paz, Lower California. 



Setchell and Gardner, Alg. N.W. Amer., 1903, p. 242 ; Howe, Phyc. 

 Stud. V, 1911, p. 495; Setchell and Gardner, Mar. Alg. Gulf of Calif., 

 1924, p. 725. Colpomenia tuberculata Saunders, Phyc. Mem., 1898, 

 p. 164, pi. 32, figs. 1-3 ; Collins, Holden and Setchell, Phyc. Bor.-Amer. 

 (Exsicc), no. 826. 



The Colpomenia tuberculata Saunders is thick-walled, of general 

 globose form, but w T ith the distribution of growth areas interrupted in 

 such a way as to give rise to bullosities and tumor-like warts. Some- 

 times these swellings develop and fall out, leaving holes or lacunae, a 

 suggestion of the process in Hydrorfathrus elathratus. 



