168 University of California Puhlicatians in Botany [Vol. 8 



sought for in the varying size, shape, proportions, and modification 

 of the tips of the utricles. Further and more careful study in this 

 direction, not only of plants of different species, but also of plants 

 of varying ag-es of the same species is very much to be desired to 

 determine the limits of these variabilities. 



The reproduction of Codiuni is known in detail only for the 

 European C. tomentosum (cf. Oltmanns, 1904, p. 301, and West, 1916, 

 p. 241). In this species the spore reproduction is exclusively sexual. 

 There are two kinds of gametangia giving rise respectively to larger 

 motile 2-ciliated female gametes, and smaller but similar male gametes. 

 Conjugation has been observed and a thick walled zygote is formed 

 which germinates later. Nothing has been undertaken, thus far, 

 towards the study of the reproduction of our species. Gametangia ( ?) 

 have been seen, in most species credited to our coast, but further stages 

 have not been observed. 



Key to the Species 



1. Thallus prostrate 2 



1. Thallus erect 3 



2. Thallus applanate, flat 1. C. SetchelUi (p. 168) 



2. Thallus cushion-shaped, rounded 2. C. Ritteri (p. 169) 



3. Utricles more or less mucronate 3. C. fragile (p. 171) 



3. Utricles never mucronate 4 



4. Thallus cylindrical or flattened only below the axils 5 



4. Thallus cylindrical only at base, decidedly flattened above 6. C. latum (p. 175) 



5. Utricles 400m or more in maximum diameter 4. C. decorticatum (p. 172) 



5. Utricles 250m or less in maximum diameter 5. C. tomentosum (p. 174) 



"SfiMx^c-yn^" 



1. Codium Setchellii Gardner /^^ J^ /^ 



Plate 30, and plate 9, figs. 10, 11 ' yU^UK^zy*^^^^^ 



Thallus forming dense, compact, spongy, irregular cushions, 6-10"""-^ » 

 mm. up to 15 mm. thick, adhering firmly to rocks ; color dark glossy 

 green ; medullary filaments 12-30/i, diam. ; utricles variable in shape, 

 clavate, cylindrical, or sometimes constricted below the apex, truncate 

 or slightly rounded above, 65-75/i, wide, walls thin throughout when 

 young, the outer ends 6-16/i. thick and lamellose when older; game- 

 tangia cylindrical or slightly fusiform, 300-330/x long, 45-55fi diam., 

 growing singly on the utricles; trichomes wanting. 



Growing on rocks in the lower littoral belt. Central California 

 (possibly extending to southern California) and northward to Sitka, 

 Alaska. 



