108 FRESH-WATER ALGJE OF THE UNITED STATES. 



Grows everywhere on the sea coast and in estuaries of 

 tidal rivers. Filaments are not so irregularly inflated and 

 constricted (intestine-like) as the preceding. Many varieties 

 of these two species have been described, but being more of 

 marine than fresh-water plants, they are omitted. 



Subsection B. CLADOPHORIN^;, 



As a second subsection, are filamentous plants, articulate 

 and branched ; lower branches often assuming the character of 

 rhizomes and the distal cells often terminating in a long hair-like 

 point. The escape of microzoospores is frequently observed, 

 but copulation has not been seen; thick-walled resting spores 

 occur occasionally, but nothing is known of their origin or of 

 their development. 



Genus 16, DBAPABNALDIA, Ag. 



Filamentous, articulate, much branched ; the main stem com- 

 paratively thick, composed of large cells, mostly hyaline, with a 

 broad chlorophylose transverse band, always sterile; more or 

 less densely furnished with bright green penicellate, fasciculate 

 branchlets, alternate or opposite, composed of smaller fertile 

 cells. Terminal cells of the branchlets empty, hyaline, and often 

 elongated into a bristle. The whole plant enveloped in a soft 

 gelatinous covering ; soft and slippery to the touch. 



DRAPARNALDIA GLOMERATA, Ag. 



Filaments and primary branches nearly colorless, lower 

 articles about as long, or a little shorter than broad, more 

 or less swollen ; upper articles longer, for the most part 

 hyaline with a light green, central, narrow, transverse, 

 chlorophylose band ; always sterile ; primary branches 

 spreading at nearly right angles ; fascicles of branches ob- 

 tuse, oval, crowded, alternate or opposite. 



Syn. Conferva mutabttis, Dillw. ; Batrachospermum conglomeratum, 

 Vauch. 



In clear streamlets, slow or rapid, attached to stones or 

 water plants. Frequent and readily distinguished. 



The following, among many varieties very closely related and 

 running into one another, may be separated. 



a. genuina, Kirch. Diameter of stem about 35 /*; length, 

 the same ; primary branches close, clothed with 

 crowded secondary branchlets. 



b. remota, Bab. Primary branches remote. 



