The structural analysis was performed of cuticular apparatuses of flat worms from the genus Gicysztoria. The primitivity criteria were used to obtain morphological series reflecting the evolutionary transformations of the cuticular apparatus elements. A classification is given of the apparatuses of Gicysztoria and the scheme of their phylogenesis. The most primitive are the apparatuses consisting of separate spines. The morphological unification of spines leads to formation of appendages and spine-bearing branches. In the course of evolution the number of spines decreases and medial appendages start forming and the spine-bearing branches transform into various appendages, the appendage structure is modified.