510 PROCEEDINGS OF THE NATIONAL MUSEUM. vor,. 59. 



train of signals centering at the position of 4> (101) — was observed 

 on crystal 58 (fig. 6). This form was also identified with moderate 

 certainty on crystal 65 (fig. 22) as a well-defined face. This was 

 wholly without reflection but was approximately measured by 

 moistening with alcohol yielding the following angles : 



(101) Measured ? = 90° 00' p = 59°34' 



Calculated <p = 90° 00' p = 53° 24' 



A= 0° 00' A = 3° 50' 



In several other instances narrow and wholly dull faces were seen 

 which were thought to be this form, but owing to their failure to 

 reflect any light they could not be measured. 



j) (106) was tentatively identified as a narrow line yielding a very 

 dim and not accurately measureable signal on crystal 10, as shown in 

 figure 16. The angles obtained are as follows: 



(106) Measured ? = 90°00' p = 21°00' 



Calculated? = 90° 00' p = 18°31' 



A = 0° 00' A= 2° 29' 



/ (203) was observed twice, once on crystal 7 as a small face, some- 

 what etched and giving a faint signal, which yielded angles compared 

 as follows: 



(203) Calculated ? = 90° 00' p = 53° 07' 



Measured ? = 90° 55' p = 54° 51' 



A= 0° 55' A= 1° 44' 



This form also occurred as a well-defined though narrow face on 

 crystal B5, shown in figure 13, which gave the angles: 

 Measured ? = 89°41' p = 53°25' 



A= 0° 19' A= 0° 08' 



s (302) was found as very narrow faces, yielding poor signals, on 

 crystals B5 (fig. 13) and 39 (fig. 15). The angles are as follows: 



(302) Calculated ? = 90° 00' p = 71° 18' 



Crystal B5, measured <p = 89° 48' p = 69° 02' 



A = 0° 12' A= 2° 16' 



Crystal 39, measured ? = 90°04' p = 70° 00' 



A= 0° 04' A= 1° 18' 



§ .(308) , described as new on Westfield datolite by Gorgey and 

 Goldschmidt, was found on six crystals. It is usually present as a 

 small or narrow face, which is sometimes bright, but is more fre- 

 quently etched or "matte," yielding a dim or a red signal. It occurs 



