464 University of California Puhlications in Botany [Vol. 6 



Plants forming a dark colored, pulverulent, somewhat mucilag- 

 inous stratum, 1-4 mm. thick; single cells spherical, 8-10 {x diam., in 

 colonies very angular, 4-8/i. diam., forming spherical or variously 

 lobed, frequently entophysaloid colonies, 40-60/x, up to 200/x diam., by 

 cell divisions without rupturing the original tegument; tegvnnents 

 firm, slightly mucilaginous on the surface, yellowish brown, 2/x thick; 

 protoplast homogeneous, light blue-green; gonidia formed in un- 

 changed vegetative cells of either the small or the large colonies, 

 3-3.5 diam. 



Growing on rocks in the upper littoral belt. Carmel Bay, Mon- 

 terey County, California. Type no. 3219, W. A. Setchell. 



Pleurocapsa fuliginosa Collins, Holden and Setchell, Phyc. Bor.- 

 Amer. (Exsicc), no. 704 (not of Hauck). 



Pleurocapsa entopliysaloides is closely related to P. fuliginosa 

 Hauck (1885, p. 515, fig. 231) but differs from it in having slightly 

 larger colonies which are often entophysaloid (pi. 41, fig. 30), in hav- 

 ing a blue-green protoplast, a yellowish brown tegument, in having 

 slightly larger vegetative cells and in having gonidia develop in the 

 small vegetative cells. In this last statement concerning the size of 

 the cells, I am assuming that Hauck intended to include the large 

 spherical cells which he figures and which would ordinarily be con- 

 sidered gonidangia, in his measurement "Zellen 5-20/x dick." I have 

 examined a bit of the type material of his P. fuliginosa and find that 

 the vegetative cells of our species are slightly larger than the cells 

 which I consider to be the vegetative cells of the type. Hauck does 

 not mention gonidangia but he figures, in addition to groups of two, 

 four, to many cells, four large spherical cells, one of which is filled 

 with undoubted gonidia. The presence of these two forms and sizes 

 of cells brings up the question as to whether or not we are dealing 

 with a single species or with two species, and if the latter, the two 

 species probably belong to different genera. I have been puzzled with 

 several similar mixtures collected on our coast. I am of the opinion 

 that we have to reckon Avith two species in these cases and in the 

 ca.se of P. fuliginosa. Now that we have discovered gonidia in these 

 colonies of small vegetative cells in at least two species of Pleurocapsa, 

 viz., P. entopliysaloides, and P. gloeocapsoides, the evidence in favor 

 of considering that such mixtures as mentioned above belong to two 

 species is stronger. Either we may take this view of the matter or we 

 may note that we have two lines of development in a single species. 

 One starting with a single cell, e.g., a gonidium, and. after enlarging 

 to mature size, divides in three planes successively more or less at 

 right angles to each other, the process continuing until a smaller or 



