652 METASPERMAE OF THE MINNESOTA VALLEY. 
13. The Eastern Generic Element. 
No. of | Percent of all |Eastern per ct. 
genera. Eastern. of each. 
Monocotyledones........ .... 85 31.4 80.9 
Archichlamydeae............ 107 39.6 61.1 
Metachlamydeae.............. 78 28.9 60.9 
Total Eastern.............-. 1 es See eee 
Eastern per cent. of all genera] 66.1 |..... cee eed cee eee eee eee 
The third column of the table above furnishes the largest 
percentage figure of any of the tables. The 80.9 per cent. of 
eastern-ranging monocotyledonous genera indicates sufficiently 
the eastern preponderance of this taxonomic group, as repre- 
sented in the valley of the Minnesota. The lower percentage 
of the Metachlamydeae will be understood better in connection 
with the following table: 
14. The Western Generic Element. 
No. of | Percent. of | Western per 
genera.| all Western. /cent. of each 
Monocotyledones..............4- 36 14.1 44.8 
Archichlamydeae................ a4 45.8 34.2 
Metachlamydeae................ 63 34.4 49.0 
Total Western................ N83 jecoawgaieesgusslbomtiiine vores 
Western per cent. of all genera .| 44.8 |... 62... cece epee eee ee eee ee 
By a comparison of the two tables preceding it is noted 
that the differences are widest between the Monocotyledones, and 
narrowest between the Metachlamydeae. By genera, then, the 
Monocotyledones are most evenly distributed north and south 
while the Metachlamydeae are most evenly distributed east and 
west. The evident importance of this fact, thus determined, lies 
in the exact parallelism which it maintains with others derived 
above. The Metachlamydeae, being peculiarly the central and 
