256 A new system of Crystallographic Symbols. 
The dashes to be placed below these letters will depend, as has 
before been stated, on the situation of the primitive plane on which 
the secondary inclines. It must be remembered however, that in the 
rhombohedron, when the plane on a lateral angle cuts off a domi- 
nant plane angle, a merely is to be used ; when it cuts off the other 
plane angles, the inverted curve is to be placed below as a. Also 
in the ob. rbe. prism, if the plane on a superior lateral angle inclines 
on one of the anterior faces, the curve line, the distinguishing mark 
of the faces, is to be placed below. But if it inclines on a posterior 
face, to distinguish these from the former, the curve must be inverted. 
Thus a, a, and a (the latter for planes inclining on the base,) will 
be the symbols for the planes not intermediary about a lateral solid 
angle. 
A similar table for the octahedra, dodecahedron, and hexagonal 
prism,* will supersede the necessity of any remarks with regard to 
them. I would state merely, that in the octahedra the Roman e is 
applied to the lateral edges, the italic to the basal, the Roman a to 
the vertical solid angles, the italic to the lateral. 
1 Reg. Octahedron. 4 Rt. rbc. Oct. 
Planes P Planes P 
Edges e Anterior lat. edge e 
Solid angles a Side panics e 
2 Rt. sq. Oct. Basal edges € 
Planes P Vertical sol. angle a 
Lat. edges e Anterior basal a 
Basal“ e Lat. ce a 
Vertical sol. angle a Dodecahedron. 
Lat. ea ee a Obtuse solid angle a 
Rt. rect. Oct. Acute) (1) Sonic 
Rt. hand plane lef Edges e 
Dees a P' Hexagonal Prism. 
_ Lat. edges e Bas. plane P 
Rt. basal edge é Lat. plane ip 
Die sy ie é Lat. edge e 
Vertical sol. angle a Bas. “ e 
Basal“ 5 a Sol. angles a 
Intermediary planes on these solids are named in the same manner 
as those onthe prisms. ‘Thus inthe Rt. rect. octahedron, a plane situ- 
* The tetrahedron isnot here included, it appearing to be buta secondary to the 
octahedron. Itssymbol referred to the octahedron will be 4P. 
