A subclass of Rhizopodea characterized by lobopodia predominantly, although certain of these protozoan species also may form slender pseudopodia, or even develop several different kinds. Lobosia are divided into two orders which differ in presence or absence of a test. The Amoebida include the amebas, which do not produce a test. The Arcellinida possess a one-chambered test ranging from a predominantly chitinous to a mainly siliceous covering. Pseudopodia emerge through the aperture of the test.