118 



BULLETIN OF THE UNIVERSITY OF WISCONSIN. 



r, R (1011). 



e, iR (0112). 

 v, R 3 (2131). 



a, HR (O.ll.n.20).* 



b, HR (0.18.18.25).* 

 /, -2R (0221). 



c, 24R (24.0.24.1).* 

 8, 10R (10.0.10.1). 

 fc, IR (5052). 



S3, 1 |R2 (1123). 



f, 1R3 (2134). 

 57, l ffif (5279). 

 ^, ffif (4156). 



These forms have been determined by the following 

 measurements which are for the most part averages of 

 several readings made on corresponding angles 2 : 



Zone of e and m. 



1 Numbers used by Irby. 



2 The vicinal character of r prevented measurement, but the plane is easily identified by 

 the cleavage. The face k is determined by its zones. 



