BASE, AND ITS MODIFICATIONS. 151 



Class e. Terminal solid angles replaced by four 

 oblique planes, inclining on the obtuse edges of the 

 pyramids. 







Class/". Terminal solid angles replaced by four 

 oblique planes, inclining on the acute edges of the 

 pyramids. 



Modifications e, and f, may be distinguished from 

 modification d, by the edges of the modifying planes 

 which intersect the primary planes, not being parallel 

 to the edges of the base. 



Classes d, e, and/J would produce a series of octa- 

 hedrons with rhombic bases, more obtuse than the 

 primary. 



Class g. Obtuse lateral solid angles replaced by 

 tangent planes. 



