512 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 59. 



at (324) was observed on crystal 56 and on several similar crystals 

 from the same specimen as a very narrow line beveling the angle 

 between rn (110) and x (102). The angles are: 



(324) Measured </> = 68° 26' p = 60°47' 



Calculated <p = 67° 06' p = 58° 26' 



A = 1° 20' A= 2° 21' 



ft (454) occurred on crystal B9 as a very narrow face beveling the 

 angle between n (111) and /3 (121), as shown in figure 9. The signal 

 was so faint as to not be accurately measurable in the presence of 

 adjacent brilliant forms. The angles are: 



(454) Measured ^ = 53° 29' P = 67°28' 



Calculated «? = 51° 36' p = 68° 34' 



A = 1° 53' A = 1° 06' 



oi (Tl6) was found on but two of the crystals studied. On crystal 

 B5 it forms a very narrow line, giving a poor signal, as shown in figure 

 13, while on crystal 51 it is present as a somewhat broader face, as 

 shown in figure 17. The angles are: 



(116) Measured XI. 51 <p = 57° 35' p = 20° 25' 



B5^ = 57°56' p = 21°40' 



Average *> = 57° 45' p = 21° 03' 



Calculated <p = 57°24' p = 21° 23' 



A= 0° 21' A= 0° 20' 



B (121) was found as a distinct line, giving a poor signal on crystal 

 33, as shown in figure 24. On crystal 41, shown in figure 18, this 

 form occurred as a bright face, giving a very good signal. The 

 angles are: 



(T21) Measured XL 33 «^ = 39° 43' p = 73° 39' 



41<p = 38°07' p = 72°43' 



Average <p = 38° 55' p = 73° 11' 



Calculated ^ = 38° 12' p = 72°46' 



A- 0° 43' A= 0° 25' 



M (T22), which was first reported by Whitlock on Westfield dato- 

 lite, occurs rather frequently, especially on crystals of type 1, usually 

 as a small face, which is frequently lightly etched. Characteristic 

 outlines are shown in figures 4, 7, 18, and 23. The faces frequently 

 give perfect signals. The angles are: 



(122) Measured, maximum ^> = 37° 16' p = 58° 19' 



Measured, minimum <p = 38° 13' p = 57° 50' 



Measured , average <p -= 3 7 c 57' p = 58°09' 



Calculated *> = 38° 10' p = 58° 09' 



A= 0° 13' A= 0° 00' 



