302 PROCEEDINGS OF THE AMERICAN ACADEMY. 



series lies 10' further from the pole of the form as measured than the 

 indices (0 • 14 • 14 • 17) assigned to it by Sehaller. 



D. (0- 19-19-20). This rhombohedron was observed by Cesaro 31 

 on crystals from Arquennes, Belgium. It lies close to (0111), a form 

 noted by the same authority on several combinations from Rhisnes. 

 It should be referrred to the simpler indices. 



Hypothetical Rhombohedrons. — The two members missing from 

 normal series N2 in the above development are 1 and 2 corresponding 

 respectively to (0334) and (0556). Parallel zones through the poles 

 of these hypothetical forms, do not suggest any simple zonal relations 

 between them and common and well established forms. The forms 

 as hypothetical ones should be rejected. 



The portion of the zone between (0111) and (0332) contains the 

 following forms: — 



Form 



( k- h- X- (a- v G- 



JOll 0-17-16 087 065 054 0-14-11 



17 8 6 5 14 



Symbol 1 tf f fi i ir 



V —Vl n I 2 2 1 6 



« T U 7 5 3 J- 5 



u 14 5 3 2 5 



2 



N 4 L\) (J) 



113 

 14' W 3 2 5 



Form 



< £■ H- tv. P- Y- p- 



(043 0-18-13 075 0-13-9 0-19-13 032 



Symbol § if 



v —vi 10 



4 18 7 13 19 3 



5 9 13 '2 



V2 — V 

 V 1 



3 



5 

 5 



8 12 



4 6 00 



2 



N 4 1 •• § 2 •• 4 (6) 



This portion of the zone is incomplete and contains the extra forms 



.17 8 1 19 



16» 7 ancl 13- 



f). (0- 17-17- 16). This rhombohedron was observed by Cesaro 32 

 on crystals from Rhisnes, Belgium. It lies close to (0111) and, like 

 (0-19 -19-20) from Arquennes, should possibly be referred to the 

 simpler indices. 



31 Cesaro, G., loc. cit. 



32 Cesaro, G., loc. cit. 



