Jovan Hadži theories of animal evolution. He devised a system of classification in which he divided the animal kingdom into six phyla: Protozoa, Parazoa, "Ameria" (animals with no segments), "Oligomeria" (animals with few segments), "Polymeria" (animals with many segments) and Chordata. His choice of characters important for classification was generally discredited by his contemporaries, and the system was never accepted by zoologists. However, due to its simplicity, the system was widely used in science education in former Yugoslavia. His other major theory was that of the origin of metazoa - he developed an existing hypothesis stating that the first multicellular animals resembling
Bacterial phyla Several candidate phyla (Microgenomates, Omnitrophica, Parcubacteria, and Saccharibacteria) and several accepted phyla (Elusimicrobia, Caldiserica, and Armatimonadetes) have been suggested to actually be superphyla that were incorrectly described as phyla because rules for defining a bacterial phylum are lacking. For example, it is suggested that candidate phylum Microgenomates is actually a superphylum that encompasses 28 subordinate phyla and that phylum Elusimocrobia is actually a superphylum that encompasses 7 subordinate phyla. , there are 30 phyla in the domain "Bacteria" accepted by LPSN. There are no fixed rules to the nomenclature of bacterial phyla. It was proposed that the suffix "-bacteria" be