45 

 NOTES ON CYANOPHYCE.E.— III.. 



BY W. A. SKTCHELL. 



Calothriz parietina (Nseg.) Thuret is a very va,rial)le species, 

 as is clearly set forth by Bornet and Flaliault (Kev. Nost. Het.; I, 

 367), yet it is fairly easily recognized when its chief characteristics 

 are once determined. Farlow was the first to publish it from North 

 America. He found it growing in Nobska Pond, near Wood's 

 Hole, Mass. (cf. N. E. Algie, 40). Since then it has been found in 

 various places in Massachusetts, Connecticut, and California by the 

 writer and others. It has been distributed from this country under 

 the following names: — 



Calothrix parietimi, Holden, Phyc. Bor.-Amer,, No. 12. Tilden, 

 Amer. Alga, No. 164. 



Porphyrosiphon Notai^sii, Tilden, Amer. Algse, No. 65. 



Dichothrix UUihen-ns, Tilden, Amer. Algfe, No. 288. 



Calothrix thermalis, Tilden, Amer. Algse, No. 287. 



Wolle has also distributed specimens under the usime of Masti- 

 gonema aespitosum (No. 18), and there is little doubt but that this is 

 the form referred to by him under this name in the Bulletin of the 

 Torrey Botanical Club for 1877 (6, 138) and also under the name 

 of Isactis csespitosa in his Fresh Water Algse of the U. S. (p. 245, 

 pi. 176, f. 5 and pi. 178, f. 1-3.) 



C. parietina may be entirely free from incrustation, or it n)ay be 

 very thoroughly incrusted with either lime or silica. It is seldom, 

 if ever, branched, but the hormogonia in the incrusted specimens 

 attach themselves very often to the sheaths of the older filaments 

 and resemble branches very strongly indeed. Intercalary hetero- 

 cysts do occur in C. parietina, but they are not at all common. The 

 species is usually readily distinguished by its laraellose, brown, and 

 more or less ochreate sheath, but these characters may be at tin)es 

 more or less obscure. 



Contributions from the Botanical Laboratories of the University of 

 California, No. .5. 



Erythea, Vol. VH, No. 5 [1 May, 1899]. 



