FEWKES: A PREHISTORIC STONE MORTAR 459 



what appears to be a large face intersecting the prism edges at 

 90°. A careful examination shows that this large terminal plane 

 is striated, the faces of the striatums belonging to the form 

 (T02). (See fig. 2.) All the crystals measured are twinned and 

 show faces of the two constituent individuals. 



The polar elements derived from the measurements are as 

 follows : 



Vo = 1.0512; q = 0.9501 ;e = 0.45071 ; M = 63°13' 



corresponding to the axial ratios, 



a:b:c :: 1.0125: 1: 1.0643; = 63°13'. 



In table 1 are indicated the forms observed and the polar 

 angles <f> and p measured and calculated for the elements indi- 

 cated above. The number of faces observed for each form on 

 the four crystals measured is shown in the second column. 



ETHNOLOGY. — A prehistoric stone mortar from southern Ari- 

 zona? J. Walter Fewkes, Bureau of American Ethnology. 



Prehistoric buildings in the Gila Valley differ from those of 

 southern Colorado and New Mexico in materials employed, 

 form, and details in construction and arrangement of sacred and 

 other rooms. There are less pronounced differences in ceramics, 

 implements, and household utensils of the two areas. The ac- 

 quisition of a fine, characteristic stone mortar from near Casa 

 Grande has led me to describe it and incidentally to refer to a 

 feature in this object not shared with mortars from the true 

 Pueblo area. 



A short time ago I obtained from Mr. John Miller, one of my 

 workmen at the Casa Grande ruin in 1907, a stone mortar of 

 more than ordinary interest on account of its artistic character. 

 This object was found 5 miles south of the Picacho reservoir, 

 Arizona, where there are traces of ancient settlements. It is 

 made of a light-colored volcanic stone of circular shape and has 

 a flat base with a cavity or depression on the opposite face. The 



1 Published by permission of the Secretary of the Smithsonian Institution. 



