350 PROCEEDINGS OF THE AMERICAN ACADEMY. 



on the combination are fairly_good. _ The pole of the form marks the 

 intersection of the zones [0443 : 4041] and [0665 : 1120]. There is, 

 however, a disagreement between the observed and calculated angles 

 which is somewhat greater than the limit of fair observation and the 

 form should be classed as rather doubtful. 



K (1- 11-12 -8) = (765). This scalenohedron which was observed 

 by Palache 154 on one crystal from the Lake Superior region is regarded 

 by him as very characteristic of the region, occurring on a number 

 of crystals as rounded and broken planes. On the combination cited 

 the pole of this form marks the intersection of the zones [2131 : 3584] 

 and [3- 5-8- 13 : 0221], all the above zone-indicating forms being- 

 present. The form may be regarded as established. 



I (3-10-13-3) = (19-10-20). This scalenohedron was observed 

 by Schaller 155 on two crystals from New Mejdco. The combination 

 cited is of prismatic habit, the form (3-10-13-3) lying in the zone 

 [lOll : OlIO], both zone-indicating forms present. The form, further- 

 more marks the intersection of the zones [0772 : 3361], [0551 : 3031] 

 and [3211 : 3472]. It should be classed as probable. 



© (3 -61 -64 -26) = (31-28-33). This scalenohedron was observed 

 by Cesaro 156 on crystals from Rhisnes, Belgium. The Miller indices 

 corresponding to this form are quite complex and the zonal relations 

 poor. Moreover the form was observed as a multiple series of planes 

 producing a number of reentrant angles, a condition unfavorable to 

 exact measurement. The form should be classed as doubtful. 



U (16-59-75-17) = (36-20-39). This scalenohedron was recorded 

 by Gonnard 157 on crystals from Couzon, Rhone, France. Like the 

 preceding form this scalenohedron does not reduce to very rational 

 Miller indices, nor does it fall in any well marked zone.__The pole of 

 the hypothetical scalenohedron (9 • 35 • 44 • 10) = (21 • 12 • 23) lies within 

 31' of <p angle and within 2' of p angle of that of (16 • 59 • 75 • 17). The 

 above hypothetical form also marks the intersection of the _zones 

 [0772:1010], [3142:1341], [3031 :_0_551] and [1431 : 16-7-23-3]. 

 It is possible that the indices (9-35-44-10) should be substituted for 

 (16-59-75-17). 

 I) (3-16- 1~9- 2) = (8- 5 -IT). This scalenohedron was observed by 



154 Palache, C, loc. cit., Fig. 13. 



155 Schaller, W. T., Zeit. f. Kryst., 44, 325. 



156 Cesaro, G., loc. cit., page 272, Fig. 52. 



15 7 Gonnard, F., Bull. Soc. fr. Min., 20, 330 (1897). 



