U. S. NATIONAL MUSEUM 



BULLETIN 149, PLATE 31 



(1). MiCROSECTION OF PHONOLITE TUFF. HEGAU. GERMANY. (AFTER 

 GUSHING); (2). GHONDROIDAL FORM IN BASALTIC TUFF, (AFTER 

 FOYE) 



For explanation of plate see pages 52 and 53 



