SUBGROUPS AND GENERA OF THE THIOBACTERIALES 469 



Tribe IV. Amoebobacterieae Trib. nov. 



Synonyms : 



Amoebohacteriaceae Migula, 1900, p. 1045 



Sulphur bacteria in which the cells are united iiito families. Cell 

 division occurring only in one direction of space. 



Key to the genera of Amoebobacterieae 



I. Cells connected by plasma threads, families amoeboid motile. 



Genus I. Amoebobacter 

 U.. Cells not as I. 



A. Cells arranged in a net, united by their ends Genus II. Thiodictyon 



B. Cells not arranged in a net. 



1. Capable of swarming. Cells loosely aggregated in gelatin. 



Genus III. Thiothece 



2. Non-motile. Cells closely appressed into a colony. 



Genus IV. Thiopoly coccus 



Genus I. Amoebobacter Winogradsky, 1888, p. 71 



€!ells connected by plasma threads. Families amoeboid motile. 

 The cell families slowly change form, the cells drawing together into 

 « heap or spreading out widely, thus bringing about a change in the 

 shape of the whole family. In a resting condition a common gelatin 

 iS' extruded, the surface becomes a firm membrane. 



The type species is Amoebobacter roseus Winogradsky. 



Genus II. Thiodictyon Winogradsky, 1888, p. 80 



Synonym : 



Rhododictyon Jensen, 1909, p. 334 



€!ells rod-shaped or spindle-shaped, with sharply pointed ends, 

 Wf^nited into a net. The compact mass of rods finally assumes an 

 apj)earance like that of Hydrodictyon. Slight violet color. 



The type species is Thiodictyon elegans Winogradsky. 



Genus III. Thiothece Winogradsky, 1888, p. 82 



CeWs spherical, in families enclosed in a thick gelatinous cyst. 

 Cells capable of swarming and very loosely embedded in a common 

 §^Iutin. When the swarm stage supervenes, the cells lie more 



