200 FRESH-WATER ALG^ OF THE UNITED STATES. 



The only plant-form hitherto described under this genus 

 has been recognized in various parts of Europe. Our form 

 is evidently distinct. 



The generic description was prepared with the European 

 plant in view, but judging by the figures which accompany, 

 it is very vague and barely applies to our form. It is given 

 unchanged. 



There appears to exist a relationship between the Coeno- 

 bium form and Dietyosphaerium, but single clusters, which 

 are by far the most frequent, particularly north of Florida, 

 are entirely distinct. 



Genus 64, MISCHOCOCCUS, Naeg. 



Thallus dichotomously branched, bearing the terminal cells. 

 Cells globose, terminal, geminate or quaternate. Division of 

 cells in one direction. 



Propagation by zoogonidia. 



MISCHOCOCCUS CONFERVICOLA, Naeg. 



Cells globose, even, geminate, ternate or quaternate, 011 

 the tips of the branches ; bright green, delicately granular, 

 destitute of a chlorophylose vesicle ; stem hyaline, spuri- 

 ously articulated, often swollen at the angles. 



Diameter of cells, 4.5-9 //. 

 Plate CLV, figs. 36-41. 



Transcribed substantially from Babenhorst's Flora Alga- 

 rum. No specimens having been found in the United States, 

 this is given in anticipation. It appears to be common in 

 many parts of Europe. 



Genus 5, EKEMOSPHAEKA, D.By. 



Cells large, globose, free swimming; cell walls firm, with a 

 hyaline border. Cell contents green, granulose, sometimes con- 

 taining green laminae, disposed in a radiate manner. Multipli- 

 cation by division into two or four (or more) sister cells, which 

 escape by the rupture of the cell-wall. 



EREMOSPHAERA VIRIDIS, D.By. 



Cells globose, large, of a bright green color. 

 Diameter of cells, 100-150 yw. 



Occurs in small pools, sometimes in considerable numbers. 

 The extraordinary size and usually somewhat isolated 

 appearance makes it possibly related to some other algse 



