190 EEYTHEA. 



regarded it as a true Diciiothrix. The species therefore 

 should be called 



Diciiothrix Hosfordii (WoUe) Bornet. 



Calothrix Hosfordii Wolle, Bull. Torr. Bot. Club, VIII ; 

 38, 1881. 



Caloihi'ix Hosfordii Wolle, F. W. Algse U. S.; 239, PI. 

 169, fig. 1-4, 170, fig. 3-4, 1887. 



Dr. Jelyffe's plant was not only determined by Wolle, but 

 also, as Dr. Boruet points out in a letter to the writer, it agrees 

 perfectly with Wolle's descrix)tion. The trichomes are some- 

 what larger than in D. Baueriana, varying from 10-12/^< in 

 diameter, are bulbously inflated at the bases of the branches, 

 with ''skuU-cap" shaped, light-blue heterocysts and with the 

 branchlets closely placed together. In speaking of Wolle's 

 figures, Dr. Bornet remarks thatthe figures upon Plate CLXIX 

 represent accurately tiie shape of the branches but not the 

 ramification, while the figures of Plate CLXX represent very 

 well the details of ramification, but do not show the bulbous 

 bases of the branches. All the figures upon Plate CLXX are 

 from plants infested with a very slender species of Schizo- 

 thrix. 



DicJiothrix Hosfordii (Wolle) Bornet, besides occurring 

 near Charlotte, Vt. (type locality), and in Lake George, 

 N. Y., has also been found at Ann Arbor, Mich., by L. N. 

 Johnson ; near Saugus, Mass., by F. S. Collins ; and in 

 different localities near New Haven and Bridgeport, Conn., 

 by Isaac Holden and the writer. A set of the writer's speci- 

 mens has been distributed in the fifth fascicle of the Phyco- 

 theca Boreali- Americana, under No. 2. 



Sirosiphon pulvinatus of Wolle's Fresh Water Algse of 

 the United States is very evidently a tangle of forms as may 

 be seen from the description (pp. 268-270), as well as from 

 the figures (Plates 190-191). It evidently includes very 

 much licheaizad forms as well as those unaffected. The Siro- 

 siphon pidvinrdus of Brebissou and other European writers 

 is the SHgonema inrfacenm Cooke. A specimen distributed 



