24 rninrsity of California Puhlications in Botany [Vol.8 



Dirmocarpa himisiyhacrica seems closely related to Pleurocapsa 

 amithystca Rosenvinge (1893, p. 967). This is especially true of 

 the early vegetative stage aud of the beginning of spore formation 

 {loc. cif., p. 968, figs. C, D). Later developments of P. amethystea 

 depart from that of D. hemisphaerica (cf. Rosenvinge, loc. cit., figs. 

 E, F, G). 



2. Dermocarpa sphaerica S. and G. 

 Plate 5, fig. 14 



Cells solitary or contiguous, spherical, 8-16/j, diam., pale blue- 

 green ; cell wall thin, hyaline ; protoplast finely granular ; gonidangia 

 spherical, 8-16/li diam. ; gonidia angular at first, becoming spherical at 

 maturity', 2.5-3/a diam., formed by simultaneous division of the proto- 

 plast, escaping by dissolution of the entire gonidangial wall. 



Growing on various species of algae in the littoral belt, frequently 

 in salt marshes. Ranging from Whidbey Island, Washington, to cen- 

 tral California. The type material was found growing on a species of 

 Lynghya, Lands End, San Francisco, California. 



Setchell and Gardner, in Gardner, New Pac. Coast Alg. Ill, 1918«, 

 p. 457, pi. 39, fig. 14. Xenococcus Schoushoei Setchell and Gardner, 

 Alg. N.W. Amer., 1903, p. 180; Collins, Holden and Setchell, Phyc. 

 Bor.-Amer. (Exsicc), no. 554 (not Thuret, in Bornet and Thuret, 

 1880, pp. 73-77, pi. 26, figs. 1, 2). 



Dermocarpa sphaerica is the plant which has commonly passed 

 for Xenococcus Schoushoei on the Pacific Coast of North America. 

 Examination of a bit of the type material of Schousboe's Coleonema 

 arcnifera, upon which Thuret founded the genus, shows that the 

 Pacific Coast plant belongs to a different genus. Xenococcus Schous- 

 hoei, as described and figured by Thuret, has increase in the number 

 of individuals by means of vegetative cell divisions. This is the con- 

 dition in which Schousboe found the type material, the plants being 

 young and the gonidial stage having not yet appeared. Our plant 

 which has passed under the name of Xenococcus Schoushoei, does not 

 divide vegetatively, and hence belongs to the group of which Dermo- 

 carpa may be taken as a type, in which there is increase only by the 

 formation of gonidia, instead of the group of which Pleurocapsa may 

 be taken as a type, in which there is increase by both vegetative cell 

 divisions and by gonidia. 



Kirchner (1898, p. 58) and Forti (1907, pp. 119, 120) recognize 

 five genera of Chamaesiphonaceae which have no vegetative cell divi- 



