WHITLOCK. — CRYSTAL FORMS OF CALCITE. 315 



Referred to N3 this fragment of the zone is somewhat incomplete 

 and contains the extra forms jf and j| both of which fall in normal 

 series N 5 . 



Q: (19- 13-32-6) = (19-0-13). This scalenohedron was noted by 

 Hessenberg 73 on crystals from Andreasberg. Irby 74 in commenting 

 on this form in his list, states that the only determination of it is not 

 perfectly satisfactory. Sansoni 75 includes it in combination 242 

 from Andreasberg which he ascribes to Hessenberg without comment. 

 The form must be considered as rather improbable. 



77 : (23-17-40-6) = (23-0-17). This scalenohedron was described 

 by Sansoni 76 on three crystals from Andreasberg. Although the pole 

 does not lie in any well defined secondary zone, the angular values as 

 determined by Sansoni agree so well with theory as to place the form 

 beyond question. 



The following relatively steep scalenohedral forms have been re- 

 corded in the zone fragment between T : (4371) = (403) and a (1120) = 

 (101). 



This zone fragment is quite incomplete and contains the extra 

 forms %, £§, ^and ^f. 



W: (13 -11 -24 -2) = (13-0-TI). This scalenohedron has been as- 



73 Hessenberg, F., Min. Not., 4, Frankfort (1875). 



74 Irby, loc. cit. 



75 Sansoni, F., R. Accad. d. Line. Mem., 19 (1884). 



76 Sansoni, F., R. Accad. d. Line. Mem., 19 (1884). 



