2-24 FRESH -WATER ALG^ OF THE UNITED STATES. 



Hah.— In rivulis frigidis montauis Diamond Range, Rocky Mountains ; (Sereno Watson). 

 About 5 inches long, regularly constricted, simple, compressed, arcuate, in mass obscure violet; 

 papules wanting ; spores irregularly oval or subglobose. 



RemarJcs. — I have received specimens of the plant from which the ahove diag- 

 nosis was drawn, from Mr. Sereno Watson, labelled " Mountain stream, Diamond 

 Eange, altitude 6500 feet." In the dried state they are closely interwoven into a 

 dark purple, rigid thin mass. When soaked out they preserve the same color in 

 mass, but each individual stem has a general light yellowish, neutral ground tint, 

 with dark-purplish or greenish-black bands at regular intervals. At the position 

 of these bands the filament is nearly round and contracted, whilst between them it 

 is compressed and enlarged. The spores are placed, not at the swelling, but at 

 the constrictions, corresponding to the dark rings in position. They are quite 

 irregular in shape, and of a faint yellow tint. The filaments between the little 

 knots of spores appear to be hollow. Their walls are everywhere very thin when 

 compared with L. torulosa, hence they are more flaccid. The species agrees in 

 every respect with Prof. Rabenhorst's diagnosis of L. catenata, Ktz., a native of 

 cold mountain streams of Germany and Switzerland. I regret, however, very 

 greatly that I have had no opportunity of comparison with European specimens, or 

 a fuller description. 



