THE GREEN ALGAE OF NORTH AMERICA 49 



plane, exactly quadrate with squarish central opening ; included 

 in an indistinct gelatinous layer ; division on the diagonals of 

 the quadrate colony. Wis., G. M. Smith. Europe. 



ACTINASTRUM L/agerheim, 1882, p. 70. 



Cells ovoid to clavate or'subcylindrical, radiately attached by 

 their apices to form small colonies, which often remain attached ; 

 chromatophore parietal, with or without pyrenoid ; asexual re- 

 production by longitudinal and transverse division. 



KEY TO THE SPECIES OK ACTINASTRUM. 

 i. Cells elongate-clavate, 10-24 X 3-6 //, with pyrenoid. 



i . A. Ha ntzsch it. 

 i. Cells nearly cylindrical, 14-18 X 1.75-2 M, without pyrenoid. 



2. A . gracillimum. 



1. A. HANTZSCHII L,agerheim, 1882, p. 70, PI. Ill, figs. 

 25-26. Colonies usually 4-celled ; cells elongate-clavate, 10- 

 24 X 3-6 fj., with one pyrenoid, apices attenuate or acuminate, 

 membrane delicate, hyaline. St. Louis, Mo., Ada Hayden, 

 1910, p. 43. Europe. 



2. A. GRACILLIMUM G. M. Smith, 1916, p. 480, PI. XXVI, 

 fig. 23. Colonies 4-8-celled, cells elongate cylindrical or slightly 

 tapering, 14-18 X 1-75-2 /*, without pyrenoid. Wis., G. M. 

 Smith. 



Page 80 of supplement, cancel ACTINASTRUM. 



Page 171, after description of KIRCHNERIELLA, insert, 



KEY TO THE SPECIES OF KIRCHNERIELLA. 



i. Cells lunate or reniform. 2. 



i. Cells cylindrical, curved or twisted. 3. 



2. Ends of cells pointed, distant. i. K. lunaris. 



2. Ends of cells blunt, approximate. 2. K. obesa. 



3. Cells 8-10 /J. loug; ends usually recurved. 3. K. contorta. 



3. Cells 15-25 /xlong, spirally or irregularly twisted. 4. K. elongata. 



After description of Var. DIANAE, add, 



3. K. CONTORTA (Schmidle) Bohlin, 1897, P- 2O J K. obesa 

 var. contorta Schmidle, 1894, p. 44, PI. VII, fig. 2. Cells cylin- 

 drical with rounded ends, 8-10 X 0.7-2 /x, the ends hooked and 

 curved. Wis., G. M. Smith. Europe. 



4. K. ELONGATA G. M. Smith, 1916, p. 473, PI. XXIV, 

 fig. 7. Colonies of 4, 8, 16 or many cells imbedded in a copious 

 homogeneous matrix ; cells cylindrical, rounded at ends, spirally 

 or irregularly twisted into a knot-like snarl ; chromatophore 

 parietal, without (?) pyrenoid; cells 15-25 X 2-2.75 /A, colonies 

 up to 100 /j. diam. Wis., G. M. Smith. 



