1919] Setchell-Gardner : Myxophyceae 97 



Agardh, Svst. Alg., 1824, p. 70 ; Bornet and Flaliault, Rev. I, 1886, 

 p. 353; Bornet and Tliuret, Notes Algol. II, 1880, p. 159, pi. 38; 

 Setchell and Gardner, Alg. N.W. Amer., 1903, p. 197 ; Collins, Holden, 

 and Setelu'll, Phj'c. Bor.-Amer. (Exsiec), no. 1720. Conferva scopu- 

 lorum Weber and Molir, Reise durch Schweden, 1804, p. 195, pi. 3, 

 figs. 3o, 36. 



A fairly and readily recognizable species, possibly to be confused 

 with C. Crustacea when the intercalary heterocysts of the latter are 

 scanty, growing usually on rocks but occasionally on wood, seldom 

 as an epiphyte, but this condition not seen, as yet, in our territory. 



4. Calothrix Contarenii (Zan.) B. and F. 



Filaments forming a blackish green, smooth, glistening, compact, 

 orbicular stratum, parallel, erect, moderately flexuous, up to 1 mm. 

 high, 9-15/A diam., decumbent and thickened at the base; sheaths some- 

 what thick, hyaline or dark yellowish brown, homogeneous or lamellate, 

 dilated above; trichomes 6-8/a diam., prolonged above into a long, deli- 

 cate hair when actively growing; cells equaling the diameter or 2-3 

 times shorter; heterocysts 1-2, basal. 



Growing sparsely on rocks near high-tide level. Southern Wash- 

 ington, central California, southern California. 



Bornet and Flahault, Rev. I, 1886, p. 344. Rivularia Contarenii 

 Zanardini, Sulle Alghe, 1839, p. 134. 



This species is very close to the last (C scopulorum) but is to be 

 distinguished by its habit and its somewhat larger and more flexuous 

 filaments. The specimens referred here have been subject to careful 

 examination and seem rather to belong to C. Contarenii than to 

 C. scopulorum. The number of basal heterocysts in C. Contarenii is 

 given as ' ' 1-2, ' ' but there are three or more in most of our specimens. 



5. Calothrix pulvinata (Mert.) Ag. 



Filaments erect, flexuous, agglutinated into small irregular 

 fascicles, 2-3 mm. high, 15-18/a diam., slightly enlarged at the base, 

 sparingly false branched, forming expanded, spongy, dull green 

 layers; sheaths thick, firm lamellate, hj^aline or brownish; trichomes 

 8-12/a diam., olive green, attenuated into a short hair ; cells 2-3 times 

 shorter than the diameter. 



Growing on woodwork, floating logs, etc. Along high-tide line and 

 in salt marshes. Puget Sound, Washington, to central California. 



