CH. XIII 



IN THE COMPOSITAE 



127 



age IS shown even more strikingly when the mean is taken for 

 the tribes arising in eaeh sub-division of the geological periods; 

 the Mutisieae are then the only exception in the series (Table II 

 col. 4). \\hen the mean is taken for each period an unbroken 

 series, running 7-2, 5-9, 4-6, 4-3, 3-6, is obtained (Table II, col. 5). 



TABLE II 



Pliocene 

 Upper 

 Middle 

 Lower 



Miocene 

 Upper 



Middle 



Lower 

 Oligocene 

 Upper 

 Middle 

 Lower 

 Eocene 

 Upper 



Middle 

 Lo\i'er 



Cretaceous 

 Upper 



Calenduleae 



Arctotideae 



Helenieae 



Vernonieae 



Eupatorieae 



Cynareae 



Inuleae (ltd.) 

 Mutisieae 



Cichorieae 

 Anthemideae 

 Astereae 

 Heliantheae 



Gnaphalieae (ltd.) 

 Senecioneae 



Average 



Generic 



Area 



3-6 



3-8\ 

 3-6J 



4-8) 

 4-5/ 

 4-9 



5-3 

 3-9 



5-5) 

 5-6/ 

 6-2 

 6-4 



6~,\ 

 7-9i 



Average Average 



for for 



Divisions Periods 



3-6 



5-3 5 



6-2 



6-4 



4-6 



Arranging the sub-tribes within each tribe in the order of 

 origin as given on p. 125, we find that even there the series follow 

 the average generic area scries more or less. The series (Table I, 

 col. 17) for the following six tribes are unbroken in each case: ' 



Anthemideae: 6-2, 4-3. 



Inuleae (hmited): 8-4, 3-5, 3-3, 1-7. 



Cynareae: 5-9, 5-1, 4-5, 3-3. 



Eupatorieae: 5-3, 4-1, 3-3. 



Vernonieae: 5-1, 4-0. 



Arctotideae: 4-7, 3 0, 2-8. 



The Calenduleae has no sub-tribes, so that only half of the 

 fourteen tribes require special consideration. 



As we are in many cases dealing with fewer than ten genera, 

 and since a number of the sub-tribes are more than slightly 



