THE GREEN ALGAE OF NORTH AMERICA 27 



formed by successive division, released by disintegration of the 

 mother cell wall. In colonies of Rivularia Bornetiana, Mass., 

 Conn. So. America. 



Moore observed the formation of a pore in the cell wall, simi- 

 lar to that used for the exit of zoospores in the other species of 

 the genus, but no zoospores were seen in this species, nor any 

 tendency of the aplanospores to make use of the pore. He 

 suggests that zoospores, unavailable in the dense gelatine of 

 the host, have ceased to be produced, the pore remaining as 

 the only evidence of their former existence. 



DICRANOCHAETE Hieronymus, 1887, p. 293. 



Cell reniform, attached, with a single chromatophore with or 

 without pyrenoids ; with slender, dichotomously branched bris- 

 tles. Reproduction by 8-24 zoospores each with stigma, con- 

 tractile vacuole and 2 cilia. 



D. RENIFORMIS Hieronymus, 1887, p. 293 ; G. S. West, 1916, 

 p. 212, fig. 139. Cells seen vertically reniform, laterally sub- 

 hemispherical, up to 32 /A wide ; bristle arising from the base 

 and passing up by a lateral groove in the cell wall, 80- 1 60 p long. 

 Attached to submerged plants etc. Fig. 6. Maine, F. D. Lam- 

 bert. Europe. 



GLOEOCHAETE Lagerheim, 1883, p. 39. 



Cells globose or subglobose, 1-4 in a wide mucilaginous coat- 

 ing, each with i or more long, slender, tapering setae ; chroma- 

 tophore bell-shape, blue-green ; reproduction by vegetative 

 division. 



G. WITTROCKIANA Lagerheim, 1883, p. 39; G. S. West, 

 1904, p. 344, fig. 160. Cells 6-21 p. diam., setae 100-260 //. long, 

 one or more to a cell. Fig. 7. Harpswell, Maine, F. D. Lam- 

 bert, Wis., G. M. Smith. Europe. 



In spite of the color, the affinities of this plant seem to be 

 with the Chlorophyceae. 



Page 149, for Key to the Species of Characium, substitute, 



i. Growing on animals. 2. 



I. Not on animals. 3. 



2. Ovoid or broadly ellipsoid. 8. C. DeBaryanum. 



2. Elongate. n. 



3. Sessile. i. C. sessile. 



3. With a longer or shorter stipe. 4. 



4. Apex acute. 5. 



4. Apex rounded. 7. 



