From teaching experience. V. Fedorov's parallelohedra

The article draws attention to the fact that there are 5 Fedorov’s parallelohedra, and not 4, as some authors indicate: a triparallelohedron (cube), a tetraparallelohedron (a combination of a hexagonal prism and a pinacoid), 2 hexaparallelohedra (a rhombic dodecahedron and an «elongated rhombic dodecahedron», i. e . a combination of a tetragonal prism and a tetragonal dipyramid), a heptaparallelohedron (a special, with equal edges, combination of a cube and an octahedron). Hexaparallelohedra form in space similarly arranged and located “columns” (term of E. S. Fedorov). But they have different combinatorial types, cannot be obtained from each other by homogeneous deformations, and should be treated in the course of crystallography as different ones.