22 University of California PuWications in Botany [Vol.8 



until Reinseh (1874, p. 15) founded liis genus Sphaenosiphon as a 

 member of tlie "^Mflanophyceae" and described a number of species, 

 some showing gonidial stages {loc. cit. pi. 25, fig. 2c, 2d, 3c). The 

 genus was properly placed and illustrated by Bornet and Thuret in 

 the Notes algoloejiqins (1880, pp. 73-77, pi. 26, figs. 3-9). Since then 

 the number of species has been increased to over twenty and there 

 are doubtless many more awaiting discovery by careful search and 

 study. 



The cells of Derniocarpa vary from spherical, or almost hemi- 

 spherical, to obovate and pyriform, or even elongated linear, but the 

 genus possesses one seemingly certain distinction in that its cells 

 undergo no vegetative division, reproducing only by gonidia. This 

 it shares only with Cyanocystis Borzi. The difference between the two 

 genera is in the manner of the dehiscence of the gonidangia. In 

 Cyanocystis the gonidangia are circumscissile, the top separating as a 

 lid by a smooth transverse rupture. In some species of Dermocarpa, 

 the entire wall or, at least, the greater portion of it, dissolves, releas- 

 ing the gonidia, but in other species, the wall ruptures by a slit at the 

 apex. Whether these distinctions are sufficient for separating the two 

 genera will be left for future study and decision. 



Key to the Species. 



1. Cells solitary (or at most slightly gregarious) 2 



1. Cells aggregated into dense layers 4 



2. Adult cells (especially gonidangia) hemispherical....!. D. hemisphaerica (p 22) 



2. Adult cells (especially gonidangia) nearly spherical 3 



2. Adult cells (especially gonidangia) ovoid to pyriform ...4. D. suffulta (p 26) 



3. Adult cells about 2.5/a in diam 3. D. sphaeroidea (p 26) 



3. Adult cells 8-16/". in diam 2. D. sphaerica (p 24) 



4. Adult cells (especially gonidangia) narrowly to broadly pyriform 



5. D. fucicola (p 27) 



4. Adult cells (especially gonidangia) spherical to narrowly cuneate 



6. D. pacifica (p 27) 



4. Adult cells (especially gonidangia) very variable in shape in same layer 



7. D. protea (p 28) 



1. Dermocarpa hemisphaerica S. and G. 

 Plate 3, fig. 21 



Cells epiphytic, solitary, hemispherical, attached by the flat plane 

 surface, 18-21/i, diam. at the base, 10-13/x high ; contents of cell bright 

 blue-green, homogeneous; cell wall hyaline, moderately thick, homo- 

 geneous, reproduction by successive divisions of the whole protoplast, 

 forming spherical gonidia 0.8-1. 2/x, diam. 



