Differences (1) from Foraminifera; (2) from Heliozoa; (3) from Proteomyxa and Sporozoa; (4) from Myxomycetes; (5) from many Foraminifera.
I have not followed the usual classification into Gymnamoebae and Thecamoebae, according to the absence or presence of a test (perforated by one or more openings) in the active state, as such a test occurs in isolated genera of Flagellata and Infusoria, and does not appear to have any great systematic importance.
The significance of chromidia in Sarcodina (first noted by Schaudinn in Foraminifera) was fully recognised and generalised by R. Hertwig in Arch. Protist. i. 1902, p. 1.
Stolč in Z. wiss. Zool. lxviii. 1900, p. 625. Lilian Veley, however, gives reasons for regarding them as of proteid composition, J. Linn. Soc. (Zool.) xxix. 1905, p. 374 f. They disappear when the Pelomyxa is starved or supplied with only proteid food.
This genus contains two sausage-shaped, blueish-green plastids, possibly symbiotic Cyanophyceous Algae.