 
 
|  Genus (Stein, 1863 or 1862?): Ovoid; an equatorial furrow marks conical anterior and spherical posterior parts; 
in the furrow are inserted two (or more) rings of strong cilia; one directed anteriorly and the 
other posteriorly; with tentacle-like retractile processes around the cytostome (Kudo, 1966). Species: 20-31 μm long (Kudo, 1966). 20-38 μm long (How to know the protozoa, 1979). 20-30 μm long; anterior conical, posterior globose; nematodemata forked at the tip (Carey, 1992). 
 | 
 50 μm
 50 μm
 100 μm
 100 μm
 150 μm; x 400 :
 150 μm; x 400 : 
 31 μm
 31 μm
 63 μm
 63 μm
 94 μm; x 640
 94 μm; x 640
 
 
 
 
 
M. acarus Stein: Oral tentacles with capitate tip; 10-16 μm long (Kudo, 1966).