314 PROCEEDINGS OF THE AMERICAN ACADEMY. 



which the scalenohedron K: is not present, the only other scaleno- 

 hedron of the principal zone being V: (6-5-Tl-l) = (605). San- 

 soni 69 has noted the form on a crystal from Schapbachthal where he 

 describes it as vicinal to K:. The form is somewhat doubtful but 

 more probable than the two preceding. 



tp: (19- 11 -30-8) = (19-0-II). This scalenohedron was observed 

 by Sansoni 70 on crystals from Monticatini, Italy. Although this 

 form falls in Normal series N 4 it is noteworthy that the hypothetical 

 scalenohedron (12-7- 19-5) = (12-0-7) which falls in normal series 

 N3 in the above development presents better zonal relation than 

 (19 • 1 1 • 30 • 8) . The form is fairly probable. 



X : (29 • 17 • 46 • 12) = (29 • • 17) . This scalenohedron was first noted 

 by Schnorr 71 on crystals from Neumark. As noted above the hypo- 

 thetical scalenohedron (12-7-19-5) = (12-0-7) which reduces to f in 

 normal series N 3 lies between the forms <p: (19-11-30-8) = (19-0-11) 

 and x : (29-17-46-12) = (29-0-17) in the zone, possesses much more 

 rational Miller indices and lies close enough to x : to be within the limit 

 of error of an ordinary observation. It is possible that x' should be 

 referred to the simpler indices. 



p : (17-11-28-6) = (17-0-11). This scalenohedron was found by 

 Palache 72 on two crystals from the Lake Superior region of Michigan. 

 The form falls in normal series N5 and also marks the intersection 

 of at least two well defined secondary zones. The form is probable. 



Hypothetical Scalenohedron. The hypothetical scalenohedron 

 (12-7-19-5) referred to above should be retained as a hypothetical 

 form. 



The following forms have been recorded between the poles P: 

 (3251) = (302) and T : (4371) = (403) : 



69 Sansoni, F., loc. cit. 



70 Sansoni, F., Atti Ace. Torino, 23 (1888). 



71 Schnorr, loc. cit. 



72 Palache, C, Mich. Geol. Surv., 6, 16 (1897). 



