454 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



TABLE III. — Continued. 



ment was much less difficult than in the case of the Utah leadhil- 

 lite. But the crystals were so fragmentary and so complex, and there 

 was such an entire lack of features by which the forms could be 

 identified on inspection, that it was only by means of the graphic 

 treatment of the measurements in gnomonic projection that they could 

 be clearly understood. Adjustment on the goniometer was always 

 made approximately by means of the base and accurately by the 

 never-failing prism zone. 



Of the sixty-seven forms observed, fourteen were new, bringing the 

 total forms known for the mineral to seventy-seven. Of equal interest 

 with the new forms, however, was the observation on this material of 



