THE GREEN ALGAE OF NORTH AMERICA 159 



KEY TO THE SPECIES OF PALMELI.OCOCCUS. 

 i. Chrouiatophores several, no coloring matter present. 



3. P. thermalis. 

 i. Chromatophore single, usually concealed by reddish coloring 



matter. 2 . 



2. Cells 3-15 fj. diam. ; plant of greenhouses, etc. i. P. miniatus. 

 2. Cells 10-40 /j. diam. ; plant of salt marshes. 2. P. marintis. 



1. P. MINIATUS (Leiblein) Chodat, 1894, P- 429, PI. XXV, 

 figs. 11-26; 1902, p. 183, fig. 80; Phyk. Univ., No. 689; Pro- 

 tococcns viridis var. miniatus Wolle, 1887, p. 181, PL CL,XII, 

 fig. 5. Cells 3-15 /* diam., orange red, with more or less oil; 

 forming a gelatinous coating on walls of greenhouses, etc. 

 Fig. 43. Very generally distributed. 



2. P. MARINUS Collins, 1907, p. 198; P. B.-A.,No. 1316.* 

 Cells 10-40 fj. diam., including wall about 2 p thick; color 

 from deep orange to green ; aplanospores 8-64 in a cell, spore 

 wall quite thick while still in the mother cell ; mass of spores 

 retaining the spherical form long after the disappearance of the 

 mother cell wall. Among various algae in salt marsh pools. 

 Maine. 



3. P. THERMALIS G. S. West, 1904, p. 287, PI. CCCCIvXIV, 

 fig. 21. Cells 2-6 fj. diam., deep green, membrane thin and 

 firm ; chromatophores 2 or 3, parietal disks ; aplanospores 4-16 

 in a cell. In hot springs. Dominica. 



4. OOCYSTIS Nageli in A. Braun, 1855, p. 94. 



Cells ovoid ; chromatophores single or small parietal disks or 

 grains, with or without pyrenoid ; asexual reproduction by 

 division of the contents into 2-8 daughter cells, in the expanded 

 membrane of the mother cell, sometimes a third generation 

 formed before the mother cell wall breaks up. 



Quite a number of species have been described in this genus, 

 four of which have been reported in America ; it is likely that 

 others will be found. Only numbers 3 and 4 can be considered 

 as safely identified with the European forms of the same names. 



KEY TO THE SPECIES OF OOCYSTIS. 



i. Cells with a tubercular thickening at each end. 3. O. solitaria. 



i. Cells without tubercular thickening. 2. 



2. Chromatophores several in a cell. 4. O. crassa. 



*By mistake the combination Pleurococcus marinus.vras used in the 

 description in Rhodora ; the following text indicates that Palmello- 

 coccus is meant; the proper form is used in P. B.-A, No. 1316. 



