436 University of California Publioations in Botany [^'^ol. (> 



method of the increase in the number of cells of the plant, or colony 

 as it may be called, certainly is different from that of Chlorogloea 

 lutea, which has cell division in three or more planes. 



Howe (1914, p. 13) has described a plant which is very similar to 

 Chlorogloea lutea. He placed it in the genus Chlorogloea, and its 

 being wholh' within the frond of the host, he called it C. endophytica, 

 and stated that it was \Qvy close to Chlorogloea tuberculosa (Hansg.) 

 Wille, differing however "in its endophytic habit, and in its less 

 distinctl}" seriate arrangement of the cells, the softer gelatinous walls 

 soon allowing the cells to become inordinate." He stated further 

 that "cell divisions apparently' occur in various planes." Chlorogloea 

 lutea differs from Chlorogloea endophytica in being only partially 

 endophytic, in having smaller cells, in building up larger colonies, and 

 distinctly having cell divisions in all directions. 



Xenococcus chaetomorphae Setchell et Gardner sp. nov. 



Plate 36, figs. 2-4 



Cellulis vegetativis in forma magnitudineque maxime variabilibus, 

 aliis sphericis aliis maxime angularibus et in dimensionibus variis 

 aequalibus, sed nonnullis longis angustisque, et utroque fine ut supra 

 visis acute attenuatis, ad 25/x in diam. verticali, cellulis angustioribus 

 ad 45/A longis ; gonidangiis in forma ut cellulis vegetativis ; gonidiis 

 per partitiones repetitas contentus toti formatis ; cellulis omnibus 

 laete caeruleo-viridibus. 



Vegetative cells extremely variable in shape and size, some 

 spherical, some verj' angular and of nearh^ equal dimensions, and 

 some long and narrow, tapering to sharp points at both ends as seen 

 from above, up to 25/a in vertical diameter, the narrower cells up to 

 45/it long ; gonidangia the same shapes as the vegetative cells ; gonidia 

 formed by successive divisions of the whole protoplast ; color bright 

 blue-green. 



Growing on Chaetomorpha aerea in a pool near high tide limit. 

 Cypress Point, Monterey County, California. 



The first mention of the genus Xenococcus was that by Thuret 

 in 1875 (Essai, p. 373). He did not, however, diagnose the genus 

 nor mention a type species at that time. Tiie genus was founded by 

 him in 1880 (Bornet and Thuret, Notes algol., fasc. 2, pp. 73-75, 

 pi. 26, figs. 1-2) based upon Xenococcus Schousboei Thuret, which 

 is Schousboe's Coleoncnia arenifera, as the type species, but even in 

 this publication he neglected to give a definite generic diagnosis. 

 Gonidia were not discovered in the species by him, but from his state- 

 ments and figures it is clear upon what vegetative characters he based 



