Those that are usually dwelt on are treated with the Rotifers and Nematoda and Turbellaria.
"Encyclopaedia Britannica, 11th Edition, Volume 11, Slice 5" by Various
The form of the lumen, as already pointed out by Grube, resembles that of the Nematoda.
"The Works of Francis Maitland Balfour, Volume 1" by Francis Maitland Balfour
Acronyms in column 1 indicate kingdom and phylum the organisms belong to: AA - Animalia Arthropoda; AB - Actinum Bacteria; AC - Animalia Chordata; AN - Animalia Nematoda; FA - Funghi Ascomycota; PB - Bacteria Proteo; PM - Plantae Magnoliophyta.
Protein Interaction Networks are Fragile against Random Attacks and Robust against Malicious Attacks