192 FRESH-WATER ALGM3 OF THE UNITED STATES. 



Genus 55, SCHIZOCHLAMYS, A. Br. 



Cells globose, either single or 2-4 associated in families, the 

 same as Tetraspora, and separated from that genus by the divid- 

 ing of the cell membrane into two or four parts. This splitting 

 and peeling of the membrane of the cells either coincides with a 

 division of the internal cell mass or it occurs without any such 

 division. 



Having seen this form repeatedly, usually associated with 

 Tetraspora, and of the same general structure, same color or 

 shade of green, same size of cells, dividing in the same way, in 

 the same water and side by side, it has become evident, it is 

 nothing more nor less than a form of it. 



Plate CLXII, fig. 7, cells of different sizes and in different 

 stages of peeling, and dividing ; fig. 9, another form, green, 

 corresponding with Chroococcus dicorticans, A. Br. , among the 



Cyanophyceae, but doubtless also a Tetraspora. 







Genus 56, PALMELLA, Lyngb. 



Cells globose, oval or oblong, chlorophyl-green, but sometimes 

 changes to orange or reddish color, surrounded with a more or 

 less thick integument, generally very soon confluent into firm 

 or soft shapeless jelly masses. Division of the cells alternately 

 in all directions. 



The forms under this genus, like those of the preceding genera, 

 Tetraspora, Protococcus and others, belong to the uncertain con- 

 ditions of the Protophyta, arrested polymorphous forms, all multi- 

 plying rapidly by the process of cell multiplication without 

 developing, for a protracted period, the true plant. What the 

 particular plants may be to which these Palmetto, forms indivi- 

 dually belong has not been determined. We hold farther opinion 

 in abeyance, in hopes of more light, and meanwhile record such 

 forms as occur. 



PALMELLA MUCOSA, Kg. 



Thallus expanded, irregular in form, rather soft gelatinous, 

 dull or olive green, cells spherical or broadly oval. Spher- 

 ical cells variable in size, 7-14 u in diameter ; oval cells 

 12-15 f* wide, about one-third longer ; cell contents more or 

 less granular. 



The former most frequent on dripping rocks, the latter on 

 wet ground. 



Plate CLXII, figs. 12, 14, the two forms. 



