the octahedron and tetrahedron French blue ; of the dodeca- 

 hedron, emerald green ; of the 3 faced octahedron and 12-faced 

 trapezohedron, deep cadmium yellow ; of the 24-f aced trapezo- 

 hedron and 3 -faced tetrahedron, burnt sienna ; of the 4-facedcube 

 and pentagonal dodecahedron, violet carmine ; and of the 6-faced 

 octahedron, 6-faced tetrahedron, and irregular 24-f aced trapezo- 

 hedron, Scheele's green. Thus there are 7 holohedral and 12 

 hemihedral forms shown. The several zone-circles are repre- 

 sented by flat steel rings surrounding the forms, those which 

 pass through the ends of the axes being coloured red, the 

 others green, and on them are marked by dots all the poles of 

 the chief forms of the cubic system, except those of most of the 

 6-faced octahedra, which lie in the triangles made by the zone 

 circles. Made by the contributor. See Science Conferences, 1 876, 

 p. 430. 



4. Models of crystals (16 small and 2 large) in wire, 

 showing planes of symmetry, axes, diagonals, &c. By 

 J. P. Stroesser. 



B. 4. 1871. Presented by the Belgian Government. 



The two large ones are : 



1. Cubic. The three axes in brass wire, and the hexakis- 



octahedron in the same; the octahedron in thick zinc 

 wire. 



2. Tetragonal. The axes in brass wire ; combination of prism 



of the first order with the pyramid in thick zinc wire. 



The 16 small are: 



1. Cubic, showing the trapezohedron and octahedron. 



2. Cubic, showing the rhombic dodecahedron and octahedron. 

 3 Cubic, showing the pentagonal dodecahedron and cube. 



4. Cubic, showing the 3-faced octahedron and octahedron. 



5. Cubic, showing the hexakis-octahedron and octahedron. 



6. Tetragonal, showing the pyramid. 



7. Tetragonal, showing a combination of a prism of the first 



order with the pyramid. 



8. Hexagonal, showing the hexagonal pyramid. 



9 Hexagonal, showing the scalenohedron with the limiting 

 rhombohedra. 



10. Hexagonal, showing the rhombohedron. 



11. Hexagonal, showing a combination of the hexagonal prism 



and pyramid. 

 12. Rhombic, showing the pyramid. 



13. Rhombic, showing a combination of a prism of the first 



order with the pyramid. 



14. Oblique, showing the pyramid. 



1 5. Doubly oblique, showing the pyramid. 



16. Loosely jointed wires forming a parallelepiped. 



