This category consists of the compound of two ikes and the compound of five ikes along with their relatives. Four regiments of two are represented here (siddo, presipsido, sne, and presipsi). All of these are orientable. The first group of four has cubic symmetry and the other group has doic. The siddo group shows up as combocells in the monster snub polychora.

**C21. Siddo** - (SID doe) snub disoctahedon. Faces are 16 triangles (20 pairs) and 24 snub triangles. It is a compound of 2 ikes. It has 24 vertices and its verf is a pentagon.

**C22. Presipsido** - (pre SIP sa doe) pentagonal retrosnub pseudodisoctahedron. Faces are 24 pentagons. It is a compound of 2 gads. It has 24 vertices and its verf is a star.

**C23. Passipsido** - (pa SIP sa doe) pentagrammatic snub pseudodisoctahedron. Faces are 24 stars. It is a compound of 2 sissids. It has 24 vertices and its verf is a pentagon.

**C24. Sirsido** - (SIR sid doe) small retrosnub disoctahedron. Faces are 16 triangles (20 pairs) and 24 snub triangles. It is a compound of 2 gikes. It has 24 vertices and its verf is a star.

**C25. Sne** - (SNEE) snub icosicosahedron. Faces are 40 triangles (20 pairs) and 60 snub triangles. It is a compound of 5 ikes. It has 60 vertices. Its verf is a pentagon.

**C26. Presipsi** - (pre SIP see) pentagonal retrosnub pseudicosicosahedron. Faces are 60 pentagons. It is a compound of 5 gads. It has 60 vertices and its verf is a star.

**C27. Passipsi** - (pa SIP see) pentagrammatic snub pseudicosicosahedron. Faces are 60 stars. It is the compound of 5 sissids. It has 60 vertices. Its verf is a pentagon.

**C28. Sirsei** - (SIR si) small retrosnub icosicosahedron. Faces are 40 triangles (20 pairs) and 60 snub triangles. It is a compound of 5 gikes. It has 60 vertices and its verf is star.

Conjugate Pairs: siddo-sirsido, presipsido-passipsido, sne-sirsei, presipsi-passipsi.

Category C3: Fivers . . . Polyhedron Page . . . Category C5: Tets and Cubes