734 METASPERMAE OF THE MINNESOTA VALLEY. 



east and west distribution of the Monocotyledones of the extra- 

 continental element indicated by the figures 93.9 and 76.7 is 

 more even than that of the Archichlamydeae of that element, 

 indicated by the figures 93.0 and 70.7. On the other hand" the 

 north and south distribution of the Archichlamydeae of the ex- 

 tra-continental element is more even than that of the Monoco- 

 tyledones, as indicated respectively, by the relations between 

 the figures 83.1 50.0 and 86.2 47.4. But in comparison with 

 the general specific elements we see, as for the Monocotyle- 

 dones, an increase in average northernness, a decrease in aver 

 age longitudinal equality of distribution and an increase of 

 lateral equality. 



Of the total specific elements the Metachlamydeae run 41.6 

 per cent, northern, 83.9 per cent, southern, 82.9 per cent- 

 eastern, 51.9 per cent, western. Of the extra- continental ele- 

 ment they run 76.1 per cent, northern, 57.7 per cent, southern, 

 92.9 per cent, eastern and 80.2 per cent, western. Of the three 

 taxonomic groups, then, the Metachlamydeae show the 

 greatest evenness of longitudinal distribution. In other words, 

 this group is least concerned in the northern-region influence. 

 Further the Metachlamydeae are most evenly distributed east 

 and west, of the extra -continental groups. As before, however, 

 but with diminished ratios, the Metachlamydeae, in comparison 

 with the Metachlamydeae of the total specific elements, show 

 an increase in average northernness, a decrease in average 

 longitudinal equality of distribution, an increase in average 

 lateral equality of distribution. These three indices of extra- 

 continental ranging in its relation to intra continental distribu- 

 tion reduce themselves to this: The extra-continental element 

 is more widely distributed intra- con tine ntally than the general 

 intra- continental element. It is more evenly distributed 

 laterally and less evenly distributed longitudinally. The three 

 taxonomic groups are in any case of different value in relative 

 cosmopolitan or endemic distribution. These differences per- 

 sist and are accentuated in the extra- continental element. Since 

 the endemic character is at once preponderantly metachlamy- 

 deous and also of the Central element, it happens that the lon- 

 gitudinal distribution of extra-continental Metachlamydeae is 

 more even than that of the other two groups, for the general 

 southern and specific northern influences are best able in this 

 group to neutralise each other. 



From the above condensed account of the extra continental 

 specific element it will be seen that every figure, in comparison 



