302 R. E. BUCHANAN 



Gaillonella Bory, 1823 



Sphaerotilus Kuetzing, 1833, p. 385 • 



Gallionella Ehrenberg, 1838, p. 166 



Leptothrix Kuetzing, 1843, p. 198 



Didymohelix Griffith, 1853, p. 438 



Crenothrix Cohn, 1872, p\ 130 



SipJionmnyxa Billroth, 1874, p. 27 



Cladothrix Cohn, 1875, p. 185 



Leptotrichia Trevisan, 1879, p. 138, in part 



Phragmidioihrix , Engler 1882, p. 19 



Kurthia Trevisan, 1885, p. 92 



Billetia Trevisan, 1889, p. 11 



Detoiiiella De Toni and Trevisan, 1889, p. 929 



Leptotrichella De Toni and Trevisan, 1889, p. 935 



Streblothrichia Guignard, 1890, p. 124. 



Eucrenothrix Hansgirg, 1891, p. 313 



Chlamydothrix Migula, 1900, p. 1030 



Clonothrix Schorler, 1904, p. 691. 



Spirophyllwm Ellis, 1907, p. 516 



Nodofoliimi EUis, 1910, p. 321. 



Leucothrix Oersted, , p. 44. 



Of these the following will be disregarded because of the in- 

 adequate characterization of genus and species: Billetia, Kurthia, 

 Siphonomyxa, Streblothrichia . 



The following are algal genera to which certain of these organ- 

 isms were incorrectly assigned: Gaillonella, Gallionella. 



The following names are invalid because of the prior use of the 

 names for distinct groups. 



Spirophyllurn Ellis, 1907, p. 516 



not Spirophylhmi Schindler, 1905, p. 82 

 Cladothrix Cohn, 1875, p. 185 

 not Cladothrix Nuttall, 1849 



The following are subgenera: Eucrenothrix, LeptotrichieUa, 

 Leucothrix. 



