34 University of California Piillic-ations in Botany [Vol. 8 



material is too sparse and scattered to admit of a very positive deter- 

 mination as to what species it really may be. There are also groups 

 of well defined vegetative cells of a species of Fleitrocapsa. Judging 

 from its present vegetative stage it seems to be undescribed. There 

 are, however, no gonidangia that we have been able to discover, and 

 as the material is very scanty we forbear naming it at present. Howe 

 (191-i, p. 12) states that he is unable to find in Miss Tilden's distri- 

 bution, mentioned above, any member of the Chlorophyceae that he 

 could interpret as being her Pringsheimia scutata forma Cladopiiorae, 

 under which name no. 382 was distributed, but suggested that possibly 

 the species referred to was that of a Derniocarpa, thus indicating tliat 

 genus as being present in the material he examined. By far tlie 

 most abundant species present in our material is no one of these bvit 

 is the plant described above. Some specimens of the host are much 

 contorted by its presence. This species seems most likely to be the one 

 upon which was based Pringsheimia scutata forma Cladophorae, and 

 is the plant, in part at least, later described and figured as Chlorogloea 

 tuberculosa by Miss Tilden (Minn. Alg., 1910, p. 46, pi. 2, fig. 42). 



4. Xenococcus pyriformis S. and G. 

 Plate 5, fig. 121 



Colonies small, single or occasionally confluent, young cells some- 

 what angular, pyriform to subspherical at maturity, 10-15|U, diam., 

 12-20/t long; protoplast bright blue-green; cell wall conspicuous, 

 dense, hyaline ; gonidangia the same shape and size as the cells ; gonidia 

 2.8-3. 5/x diam., formed by successive divisions of the protoplast. 



Growing on Rhodochorton Rothii on rock ledge along high-tide level 

 and above. Cape Arago, at the entrance to Coos Bay, Oregon. 



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

 p. 463, pi. 39, fig. 12. 



This species having cell divisions in only two planes perpendicular 

 to the substratum, thus forming colonies only one cell deep, is to be 

 placed under Xenococcus rather than under Pleurocapsa, and, while 

 its pyriform cells suggest species of Derniocarpa, it differs from mem- 

 bers of that genus in having vegetative cell division. In size and 

 shape of cells it differs from any other species of Xenococcus, as yet 

 described. 



