336 E. C. ANDREWS. 
early in the differentiation of the Order, while Australia 
was cut off at a date considerably later. 
A great differentiation of climate ensued about the date 
of the separation of Australia from Asia accompanied by a 
decided contraction of the genial and moist climate of 
earlier times. High mountains, large continents, and great 
deserts came into existence at the time of this shrinkage, 
and the uniform primary types of the Leguminosz were 
called upon either to adapt themselves to the new conditions 
or to retreat to the tropics. Instead, however, of retreat- 
ing, defeated, to the tropics, many of the uniform types of 
the legumes responded to their inhospitable environment 
in temperate regions by the development of large and 
important groups of xerophytes, such development being 
practically simultaneous in the various extra-tropical 
regions, but in different morphological directions. 
A study of Myrtacez (2) leads to a conclusion almost 
identical with that stated in the previous paragraph, the 
evidence, however, not being nearly so weighty as in the 
case of the Leguminosee. Before accepting such a con- 
clusion, however, the reader would need to be convinced 
that a genus such as Hucalyptus had not existed in Hurope 
and America in Cretaceous, Hocene, and Miocene times, 
inasmuch as systematists, such as Ettingshausenand Unger, 
have laid decided stress upon this supposed existence of 
Kucalyptus by reason of the evidence of certain fossil leaves 
of lanceolate, and somewhat falcate, appearance, in Cre- 
taceous and Tertiary beds in the Northern Hemisphere. 
Hucalyptus, however, has only in late, or recent, geological 
time, acquired the petiolate and twisted leaf stage, whereas, 
previously to that, it possessed leaves either sessile, cordate, 
opposite, thin and horizontal, more suggestive of certain 
Myrtles and Kugenias of to-day, a leaf very different from 
the present xerophytic form of many adult Hucalyptus. 
