1918J Gardner: New Pacific Coast Marine Algae II 439 



what difficult. The type material is comparatively free from foreign 

 substances and the plants of D. hemisphaerica and D. suffulta are both 

 fruiting, abundant, and eomparatively free from Chlorogloea. This 

 condition has made it possible to trace the life history of each of these 

 three species, establishing bej'ond a doubt that they are not to be 

 considered stages in the life history of a single form. 



D. hemisphaerica seems closely related to Pleurocapsa amethyst ea 

 Rosenvinge (1893. p. 967). This is especially true of the early 

 vegetative stage and of the beginning of spore formation {loc. cit., 

 figs. C, D), p. 968). Later developments of P. amethystea depart from 

 that of D. hemisphaerica {loc. eit., figs. E, F, G). 



Dermocarpa pacifica Setchell et Gardner sp. nov. 

 Plate 37, figs. 22-24 



Cellulis in coloniis ad 200ju. diam., in forma e fere sphericis, late 

 ovatis aut pyriformihus ad anguste cnneatis variantibus, 30-45/i. altis, 

 20-35/x diam.; parietibus cellularum crassis, liyalinis, homogeneis; 

 contentu cellulaiiun primo laete caeruleo-viridibus aut olvaceo-viridi- 

 bus, aetate provecta, fuscescentibus ; gonidiis numerosis, 2;u, diam. 



Cells aggregated into colonies up to 200/x diam., varying in shape 

 from nearly spherical, broadly ovate or pear-shaped, to narrowly 

 wedge-shaped, 30-45/a long, 20-35ju, diam. ; cell walls thick, hyaline, 

 homogeneous; cell contents bright blue-green or olive-green when 

 young, changing to brownish when old ; gonidia numerous, 2;u. diam. 



Growing on Chaetomorpha aerea in a tide pool near higli-tide limit. 

 Cypress Point, Monterey Countj^ California. January, 1917. 



The plants of this species were found associated with Xeiwcoccus 

 chactomorphae and the two species were so abundant as to give the 

 host a very dark color. The shapes of the cells of D. pacifica are 

 determined to a certain extent by their position on tlic host, and by 

 their age. The young cells of C. aerea are cylindrical, but they become 

 quite torulose at maturity. This change in the shape of the host 

 cells modifies the form of certain cells of the epiphyte. If the gonidia 

 of the Dermocarpa happen to locate at the cross walls when the host 

 cells are young, increase in the size of the cells of both the host and 

 the epiphyte causes the cells of the epiphyte to become much crowded 

 and thus assume a narrow wedge shape (pi. 37, fig. 22). As the cells 

 of the host plant mature and begin to disintegrate, tlie younger Der- 

 mocarpa cells that have had more room in which to expand, are 

 liberated and these become broadly oval or even spherical (pi. 37, 

 fig. 23). The cell contents become much darker and brownish at 



