€ALCITES OF NEW YORK 63 
Edge X Edge Y Edge Z 
measured Ss 35. 26 Se EY 
calculated Si BES Ss OO a ee ee 
The corresponding angular values for I: (39.15.54.8) and G: (15.7.22.2) 
are as follows: 
Edge X Edge Y Edge Z 
39.15.54.8 measured Sil 30 39 34 59 
calculated 87 143 30 464 Bl D5 
15.7.22.2 measured af 14 DS, QP 
calculated 83 50 SOM D5 BS 
From this it will be seen that the edge Y of (15.7.22.2) and the edge 
Z of (39.15.54.8) are respectively close to the edges Y and Z of 2R4/ of 
Hessenberg and that both of the former forms which were determined from 
the averaging of a number of readings for every angle agree closely with the 
theoretical values. The scalenohedron 1:.(39.15.54.8) which is new to the 
species lies closer to the zone [6281.1101] than 2R'?. The Naumann 
symbols for these substituted forms are: 
Prisms. The prism b (1010) occurs as a series of bright, sharply defined 
faces in the rhombohedral zone well developed in habit. The prism a was 
noted as a series of very narrow planes beveling the basal edges of 3: (6281) 
and principally observed in measuring the zone [2021.0221]’on crystal 10. 
Pyramid. The pyramid 7 (8.8.16.3) is present lying in zone between 
(2131) and the new negative scalenohedron (4.6.10.1). The faces are narrow 
but very brilliant and susceptible of exact determination. 
Rhombohedrons. The rhombohedral zone in this type is particularly 
rich in forms. The rhombohedrons p.(1011) and m. (4041), persistent 
throughout the occurrence, are present as well developed forms, the former 
