of Crystalline Combinations. 405 
RHOMBOHEDRAL SYSTEM. 
Relations of Edges, &c. 
‘The forms are in a parallel position. 
The faces of the rhombohedron replace obtuse terminal edges of pyramid. (S. T.) 
E. C. parallel to each other, 
a aca _.... to obtuse terminal edges of pyramid, 
as CUE to inclined diagonals of rhombohedron. 
The lateral edges of the pyramid (e) are inclined in the same direction as the edges 
of intersection (g) of the pyramid and rhombohedron. 
Phe forms are in a parallel position. 
The acute terminal edges of the pyramid in pairs replace the edges of the rhombo- 
hedron. (S. T.) 
E. C. parallel to each other, 
eA obaboviuat to edges of rhombohedron, 
Soe clad Sse to obtuse terminal edges of pyramid. 
The forms are in a transverse position. 
The obtuse terminal edges of the pyramid in pairs replace the edges of the rhom- 
bohedron. (S. T.) 
E. C. parallel to each other, 
«eee... to edges of rhombohedron, 
hoa to obtuse terminal edges of pyramid. 
The forms are co-ordinate. 
The faces of the pyramid in pairs replace the edges of the rhombohedron. 
E. C. parallel to the edges of the rhombohedron, 
.+s+e++-. to the alternate terminal edges of the pyramid (B). 
If we have also the prism © Rr, the faces pR retain their rhombic form. 
The faces of the rhombohedron replace the alternate edges of the pyramid. 
The edges replaced are alternate at the two apices. 
E. C. parallel to alternate terminal edges of pyramid, 
vseeee oe to inclined diagonals of rhombohedron. 
Meee eee eee 
