344 PROCEEDINGS OF THE AMERICAN ACADEMY. 



thetical scalenohedron (4- 7- IT -9), which lies extremely close to both 

 of the above forms, falls in zone [1123-1341] reducing to § in normal 

 series Ni._ The latter form, moreover, lies at the intersection of zones 

 [0112:4371] and [4047:0772]. The scalenohedrons (32 • 56 • 88 • 69) 

 and (4 -7- 11 -9) have the same value for <p and differ in the value of 

 the p angle by 1° 15'. In commenting on the form Palache states that 

 the faces were somewhat uneven. 



$ (12-68-80-35) = (41-29-39). This scalenohedron was observed 

 by Schnoor 129 on crystals from Neumark, Germany. The form lies 

 close to the zone [0221 : lOlO] and is unrelated to any of the important 

 poles by zone lines. The nearest rational hypothetical form in the 

 zone [0221 : lOlO] is (1673) = (11-8-TO) which develops to the term \ 

 in normal series N4. Although differing somewhat beyond the limits 

 of good observation in position from (12-68-80-35) this latter form 

 presents fair zonal relations. It might possibly be substituted. 



S (18-49-67-20) = (35-17-32). This scalenohedron was noted 

 by vom Rath 130 on crystals from Elba. Irby in commenting on it 

 observes that the indices are complex but is unable to find a substitute 

 for_it. The pole of the form lies close to (12 -32 -44- 13) in zone [4047: 

 1780] a form which has been ranked as probable in the previous dis- 

 cussion. Another possible substitution w r ould be the hypothetical 

 scalenohedron (7-20-27-8) = (14-7-13) in the zone [1123:1341]. 

 The zonal relations of both these suggested substitutions are good. 



I! (17-8-25-8) = (50-1-25). This scalenohedron is included in 

 Roger's list on the authority of Goldschmidt 131 . The form is listed 

 by Rogers with the note " Observer not known." It lies very close to 

 zone 4 and may be vicinal to (2131), if indeed it is not identical with 

 the latter form. 



129 Schnoor, Wissen. Beil. L., Programm d. Realgym. Z. Zwickau, 16 (1896). 



130 vom Rath, G., Pogg. Ann., 158. 



131 Goldschmidt, V., Kryst. Winkeltab. 



