1919] Setchell-Gardner : Myxophijceae 101 



strict sheath seem sufficient to separate this species from any of the 

 forms of C. cruMacca. Tlic c^'lindrieal hetorocysts above mentioned, 

 appearing rectanguhir to the view, are sufficiently striking to suggest 

 the specific name. 



10. Calothrix prolifera Flahault 



Layer expanded, velvety, brownish green; filaments 2 mm. high, 

 15-18/x thick, slightly flexuous, curved at the base and noticeably 

 thickened, at times falsely branched, branches emerging from beneath 

 a heterocyst after the fashion of Tolypothrix; sheath thick, lamellate, 

 firm, man}' times ocreate, with the ocreae dilated and lacerate ; above 

 hj'aline, below j-ellowish ; trichomes 8-12/* thick, bright verdigris green, 

 attenuated at the apices into hairs, cells 3-4 times shorter than the 

 diameter; heterocysts basal (1-2) and intercalary (numerous). 



Growing among other algae on boards in salt marshes. San Fran- 

 cisco Baj^, California. 



Flahault, in Bornet and Flahault, Rev. I, 1886, p. 361. Calothrix 

 Crustacea f. prolifera Collins, in Collins, Holden and Setchell, Phyc. 

 Bor.-Amer. (Exsicc), no. 1168. 



This is one of the near relatives of Calothrix crtistacea which helps 

 to make the whole Crustacea group of species (or varieties?) puzzling. 

 At times this species is well developed and seemingly distinct, but the 

 specimens referred to it here are too close to C. Crustacea to be at all 

 satisfactorily placed under a separate species. The same, however, 

 may be said of specimens often placed under both C. fasciculata and 

 C. vivipara. It has seemed best to continue the Bornet and Flahault 

 arrangement for the present, or until culture experiments can be car- 

 ried out to determine the polymorphism that may exist. 



11. Calothrix vivipara TIarv. 



Filaments decumbent and intricate at the base, becoming erect 

 and parallel, 3-5 mm. high, 12-24/* diam., somewhat flexuous, false 

 branching numerous and usually in pairs as in Scytonema, forming 

 broadly expanded, velvety coating on rocks; sheaths fairly thick, 

 somewhat mucous, homogeneous, hyaline, or becoming yellowish 

 brown ; trichomes olive green, 9-15/* diam., gradually attenuate from 

 the base upward, prolonged into a hair; cells quadrate or shorter than 

 the diameter; heterocj'sts basal or intercalary, 2-4 seriate. 



