BASE, AND ITS MODIFICATIONS. 141 



Class c. Terminal solid angles replaced by two 

 planes, resting on the narrow planes. 





Class d. Terminal solid angles replaced by four 

 oblique planes. 



The new figures would be octahedrons with 

 rhombic bases. 



Class e. Solid angles of the base replaced by 

 single planes, whose edges are parallel to the edges 

 of the pyramids. 



Class f. Solid angles of the base replaced by 

 single planes, inclining on the greater edges of the 

 base more than those of modification e. 



