THE GREEN AI.GAE OF NORTH AMERICA 151 



red stigma ; also the division of the protoplasm of an adult cell 

 into several daughter cells ; apart from this, the development is 

 unknown. 



9. C. ACUMINATUM A. Braun in Kiitzing, 1849, p. 892 ; 

 Hydrocytium a cumin a him A. Braun, 1855, p. 26, PI. II. A. 

 Cells 35-40X15-20 /A, oblong or ovoid, apex shortly acuminate, 

 stipe short, sometimes slightly swollen at the base. Mass. 



1 \nrope. 



10. C. CYLINDRICUM Lambert, 1909, p. 65, PI. 79, figs. 10-13 ; 

 P. B.-A., No. 1269. Cell 24-430/11 long, 10-20 /xdiam., cylindrical 

 with rounded apex ; tapering at the base into a short stipe, 

 without basal disk. On the minute crustacean Branchipus 

 vernalis. May. Mass. 



11. C. PRINGSHEIMII A. Braun, 1855, p. 106 ; Wolle, 1887, 

 p. 177, PI. CLIX, fig. 3 ; Wittr. and Nordst., Alg. Exsicc., 

 No. 153. Cells 20-25X6-10 p., erect, somewhat oblique, ovoid or 

 lance-ovoid, shortly acuminate, apiculum usually oblique ; stipe 

 short, expanding below into a minute, yellowish disk. Mass., 

 Pa . Europe. 



12. C. GRACILIPES Lambert, 1909, p. 65, PI. 79, fig. 3-6 ; 

 P. B.-A., No. 1270. Cell regularly curved, 80-480 /x long, 7-13/4 

 diam., middle part fusiform, tapering above into a long seta, 

 below into a long filiform stipe, attached to the substratum by 

 very minute rhizoids. On Branchipiis vernalis. Fig. 36. May. 

 Mass. 



7. CODIOLUM A. Braun, 1855, p. 19. 



Frond unicellular, ovoid to clavate or sub-cylindric, the cell 

 wall prolonged below into a longer or shorter stipe, attached by 

 a simple or forked expansion ; chromatophore covering the cell 

 wall or more or less broken, with several pyrenoids ; asexual 

 reproduction by quadriciliate /oospores, many in a cell ; also by 

 larger aplanospores (?). 



The structural plan of all the species of this genus is identi- 

 cal ; a deep green cell with thick wall, prolonged below into a 

 slender, colorless stipe ; but the proportions and dimensions 

 vary very much. The colored part, known as the clava, may 

 be broadly oval, up to 120 p. diam. ; or it may be almost 

 cylindrical, not over 25 p diam. The total length varies be- 

 tween 175 and 2700 p., the shorter forms having the largest 

 diameter of clava, and the longer forms tapering very gradually 

 from the base to the only slightly clavate apex ; in these slender 



