472 R. E. BUCHANAN 



Key to the genera of Rhodobacteroideae 



I. Cells united into families. 



A. Cells rod shaped, many embedded in the same slimy capsule. 



Genus I. Rhodocystis 



B. Cells spherical or short rods. 



1. In chains, each chain surrounded by a capsule. 



Genus II. Rhodonostoc 



2. Cells free Genus III. Rhodosphaera 



C. Cells free and elongate. 



1. Cells not bent. 



a. Non-motile Genus IV. Rhodobacterium 



b. Motile Genus V. Rhodobacilbis 



2. Cells bent or curved. 



a. Cells short, comma shaped, with single polar flagellum 



Genus VI. Rhodovibrio 



b. Cells spiral, with polar flagella. .Genus VII. Rhodospirillum 



Genus I. Rhodocystis Molisch, 1907, p. 22 



Cells rod-shaped, dividing in only one plane embedded in a 

 common slimy capsule. 



The type species is Rhodocystis gelatinosa Molisch. 



Genus II. Rhodonostoc MoHsch, 1907, p. 23 



Cells spherical or short rods, in rosary like chains, and embedded 

 in a common gelatinous capsule. 



The type species is Rhodonostoc capsulatus MoUsch 



Genus III. Rhodosphaera gen. nov. 



Synonym : 



Rhodococcus Molisch, 1907, p. 20 

 not Rhodococcus Zopf, 1891, p. 28 



Cells spherical, non-motile, free not united into families. 

 The type species is Rhodosphaera capsulatus (Molisch) Buch- 

 anan. 



Genus IV. Rhodobacterium Molisch, 1907, p. 16 



Rod shaped cells, non-motile, not united into families. 



The type species is Rhodobacterium capsulatum Molisch. 



