230 ALBERT JOHANNSEN. 



of dropping all the rocks of the monzonitic series, others of retain- 

 ing all; some favored dropping the quartz-monzonites but not 

 the monzonites, others dropping the monzonites but not the 

 quartz-monzonites. During the past year, while the foregoing 

 paper was awaiting its turn for publication and while going through 

 the press, the writer collected and determined many more modes 

 and found that the monzonitic group is unnecessary except pos- 

 sibly in the granite-granodiorite and syenite-diorite series. Now 

 apparently the only monzonites which anyone desires to retain 

 are those of these two groups. Consequently the writer believes 

 the following, changes will satisfy all sides. 



All classes and orders are to be subdivided as stated on pages 

 38 to 40. Families are to be divided and numbered hereafter 

 as shown in Figure 7 instead of as in Figure 4, the divisions 



o . 



1234 



5678 



9 10 II 12 



13 14 IS 16 



17 18 19 20 



21 22 23 24 



25 



Fig. 7. — The new subdivisions for families 



being at 0-5-50-95-100. In the case of the quartz-monzonites- 

 granodiorites, and syenites-monzonites-monzodiorites (Families 

 7-8-9, and 12-13-14, Fig. 4), subdivisions may be introduced if 

 desired with the 0-5-35-65-95-100 per cent limits as before. In 

 such cases they will be numbered, to conform with the new family 

 numbers, 5, 6', 6-7', 7^,8, 9, 10', lo-ii', 11', 12. Therefore, 

 for example: 



226 is normal granite with the Kf-Plag ratio between 95-5 

 and 50-50. 



2210 is normal syenite with the same Kf-Plag ratios. 



