1 12 Marshall Ward, — On the Characters , or 
Leptothrix (Kg. emend.). Filaments very thin 
and long. 
Beggiatoa (Trev.). Filaments thicker, and long. 
(ii) Filaments cylindrical, containing phycochrome, evi- 
dently segmented. Reproductive cells unknown. 
Hypheothrix (Kg.). 
Oscillaria (Bose.), &c. 
(iii) Filaments cylindrical, segmented, and forming 
gonidia. 
Crenothrix (Cohn). Colourless. 
Chamae siphon, &c. Containing phycochrome. 
(iv) Filaments spirally twisted 
* Devoid of phycochrome. 
Vibrio (Ehr. emend.). Filaments short, slightly 
undulated. 
Spirillum (Ehr.). Filaments short, spiral, rigid. 
Spirochaete (Ehr.). Filaments long, spiral, flexile. 
** Containing phycochrome. 
Spirulina (Link). Filaments long, spiral, flexile. 
(v) Filaments moniliform. 
Streptococcus (Billr.). Without phycochrome. 
Anabaena (Bory). 
Spermosira (Kg.), &c. 
j. Containing phycochrome. 
(vi) Filaments tapering to the apex, like riding-whips. 
Mastigothrix , &c. 
(/3) Filaments joined into zoogloea-masses by intercellular 
substance. 
Myconostoc (Cohn). Filaments cylindrical, colourless. 
Chthonoblastus | (Kg.), &c. Filaments cylindrical, 
Limnochlide j and containing phycochrome. 
Nostoc, Hormosiphon , &c. Filaments moniliform, 
and with phycochrome. 
Filaments tapering, like 
riding- whips, and contain- 
rome. 
B. Filaments branched falsely, 
(a) Without phycochrome. 
Cladothrix (Cohn). 
Streptothrix (Cohn), 
> Filaments cylindrical, 
in), j 
