NOTES ON CYANOPHYCK^. 49 



or less intertwined and about 16^i in diameter. These basal fila- 

 ments branch in a geminate fashion and the branches are erect 

 and twisted together into Syraplocoid tufts, 8-15 rum. high. The 

 erect filaments, seldom or only singly branched, are 12-16// in diam- 

 eter. The trichomes, 4-8/^ in diameter, are olivaceous to yellow-green. 

 Cells from one-half to three times as long as broad, 4-8// broad and 

 3-12/x long, uniformly coarsely granular. Heterocysts from discoid 

 to quadrate in the younger parts of the filaments, to cylindrical in 

 the older parts, colorless. Sheaths firm, stratified with parallel 

 layers, colorless, soon becoming deep yellowish brown. 



This species is most nearly related to Scyt. ocellatum Lyngb. but 

 difiers from it in habit, height, proportional length of cell and 

 character of heterocyst (cf. Plate III. fig. 3). 



Scytonema occidentale sp. nov. The material, upon which 

 the new species here proposed is based, was collected on one of the 

 earliest collecting trips taken by the writer in California. It grew 

 upon the bare smooth rock bed of La Jota Creek, just above the 

 Falls, on Howell Mt., near St. Helena, Napa County. There was 

 not very much of it and it formed tufts of a somewhat rigid con- 

 sistency and of a decidedly black color. The filaments are decum- 

 bent at the base and branched in the characteristic Scytoneraatoid 

 fashion. They measure 36// in diameter. The branches are usually 

 in pairs, erect and flexuous, 21 to 27// in diameter, and either free 

 or included for a longer or shorter distance within a common 

 sheath. The sheaths are thick, gelatinous, rugose, and made up 

 of parallel layers, of which the innermost turn blue with the 

 Chlor-Zinc Iodine. The trichomes are 18-30// thick and of a 

 grayish violet color. The ordinary cells of the trichome are 

 9-12// long, but those of the hormogoiiia are much shorter, being 

 at times as short as 3//. Scyt. occidentale belongs clearly to the 

 subgenus Euscytonenia of Bornet and Flahault and comes nearest 

 to Scyt. stuposum (Kuetz.) Bornet, but difiers from it in the shorter 

 cells of the trichome. Dr. Bornet has kindly pointed out the dis- 

 tinguishing characteristics of the species and has embodied them in 

 the following Latin diagnosis : — 



"Csespitosum, e fills basi decumbentibus pseudoramosis (36^ 

 crassis), ramis ssepius geminis, erectis, flexuosis (21 ad 27/j. crassis), 



