BASE, AND ITS MODIFICATIONS. 155 



Class I. Obtuse lateral solid angles replaced by 

 four oblique planes, inclining on the obtuse edges of 

 the pyramids. 



Class m. Obtuse lateral solid angles replaced by 

 four oblique planes inclining on the edges of the 

 base. 



The edges of planes /, and m, intersect the primary 

 planes in lines which are not parallel to the primary 

 edges of the pyramids. 



The new figures resulting from classes #, I and m, 

 would be octahedrons, more acute than the primary, 

 with rhombic bases. 



Class n. Acute lateral solid angles replaced by 

 tangent planes. 



