DE. A. W. HOEMANX ON THE PHOSPHOEIJS-BASES. 
441 
According to Weiss: — 
«: c=l: 0-3984: 0-8321; aoc=lld° 15'. 
Forms observed : — 
aicob’.ooc; ooa:oob:c; a:b:coc; — a:oob:c; —^a:oob:c; —a\b\\c. 
According to Levy : — 
MM=47°33'; MP=99°45'; : 7^=1 : 0-7730. 
Foi-ms observed: — 
A', P, M, a', V. 
Combinations observed : — 
001, 10 0, 110 (Fig. 23). 
001, 101, 110 (Fig. 24). 
10 0 , 001 , To 1 , 110 (Fig. 25). 
10 0,001,101,110; Tl 2 (Fig. 26). 
10 0, 001 , To 1 , 110 , 201 , 112 (Fig. 27). 
Pig. 23. Pig. 24. Pig. 25. 
The cr) stals sometimes present the appearance of trimetric crystals (Fig. 25), some- 
times they are flattened parallel with 0 01, and considerably elongated in the direction 
[0 1 0] (Figs. 23, 24). The faces 112 are rounded off and cannot be well measured, 
although it is possible to verify the zones to which they belong : some of these faces are 
occasionally wanting, and many of the cry stals present only two of these faces (Fig. 27). 
Cleavages 10 0 and 0 01 distinct, and easily obtained. 
Pig. 26. Pig. 27. 
The optical axes are situated in the plane of symmetry, viz. 010. The bisecting line 
is not very far from normal to 1 0 1. A system of rings is observed both through the 
MDCCCLX. 3 N 
