EXPLANATION OF PLATE XLIX. 



Orthoclase. 



Fig. 1. liaveno twin. Obuii. 



Fig. 2. Baveno triplet or combined Baveno and Manebach twin. Oban (?). 

 Fig-!. 1 and 2, -which are about four times natural size, are bounded by 

 the faces c and h, whicli are placed perpendicular to tlie plane 

 of the paper. 



Fig. 3. Grroup of orthoclase and quartz crystals, about twice natural size ; 

 the largest Carlsbad twin consists of the forms e, h, m, x, o ; the 

 Manebach twin is separately drawn in PI. xlviii., fig. 5. 

 Bolivia. 



Fig. 4. Right-handed Carlsbad tw in ; about twice natural size. Bolivia. 



Fig. 5. Left-handed Carlsbad twin ; about four times natin-al size. Uralla. 



Figs. 4 and .5 have the forms c, b, m, x, if, o. 



(For indices see Explanation to Plate xlviii). 



