ARCELLA                                              
                       
                      Phylum - Protozoa
              Sub-phylum  - Sarcomastigophora : Locomotion by pseudopodia or flagella.
                      Class     - Sarodina : Locomotion by pseudopodia.
               Sub-class     - Rhizopoda : Protoplasmic processes various but no central filament.
               Order           - Amoebina : Pseudopodia short, blunt and lobose.
               Genus          - Arcella.

Arcella 
               Arcella, commonly occurs in stagnant fresh-water having much vegetation.It has a yellowish-brown,thick transparent and disc-shaped shell around itself. It carries the shell with it during locomotion.The shell is made up of pseudochitin containing silica and iron.An inverted funnel-shaped depression is found on the ventral surface of the shell.A small mauh lies in the depression.A number of simple or branched finger-like pseudopodia arising from the mouth region serve as locomotary organs.The cytoplasm is well-differentiated into ectoplasm and endoplasm.The endoplasm contain various reserve food particles, food vacuoles and contractile vacuoles.Asexual reproduction takes place by binary or multiple fission.