334 E. C. ANDREWS. 
nections in the tropics, inasmuch as each appears to have 
descended individually from certain peculiar groups of 
uniform primary types which at one time were widely 
diffused throughout the tropics, and which show xerophytic 
modifications in varying directions in different extra- 
tropical regions such as HKurasia, South Africa, and Aus- 
tralia. 
On the other hand, the study of these two great plant- 
groups would be of little or no use in a discussion as to any 
possible former land connections between Antarctica and 
the southern continents, inasmuch as Leguminose and 
Myrtacez appear to be of tropical origin, having accom- 
modated themselves only in later geological time to tem- 
perate regions, and that with only a moderate amount of 
morphological change. 
A study of the distribution of OComposite,? however, 
would be exceedingly valuable in such a discussion because 
of the morphological similarity exhibited by certain groups 
of Compositz which are clustered at the southern ex- 
tremities of countries such as New Zealand, Australia, and 
South America. 
For the sake of brevity it has been considered advisable 
to discuss only the main principles underlying plant distri- 
bution in space, and to describe the development, in brief, 
of a few of the twenty-four tribes recorded for Leguminosz 
by the great systematist Bentham, reserving the genus 
Acacia for more detailed mention as indicating the general 
lines upon which leguminous development may have taken 
place. 
Ina problem such as that under consideration, the studies 
of geology, geography, and biology, are complementary, 
and no decided advance is to be expected without the co- 
operation of workers skilled in these branches of science. 
+ Bentham, (12) p. 504. 
