DEVELOPMENT AND DISTRIBUTION OF THE LEGUMINOSZA. 379 
Cretaceous and Post-Cretaceous Geography.—Low-lying 
lands, large epicontinental seas, and genial climate, marked 
the Cretaceous, while great continents, small epicontinental 
seas, high mountains, large deserts, glaciated poles, and a 
marked division of the climate into zones, are charac- 
teristic of the Post-Tertiary Period. The great land blocks 
of the tropics appear to have been separated from each 
other near the close ef the Cretaceous Period. The early 
Tertiary climate was also mild and genial, but a marked 
differentiation of climate was gradually introduced in the 
later Tertiary. This differentiation has been attended 
with oscillations of climate, the algebraic sum of the 
changes tending to loss of heat and moisture. 
Comparative studies.—Among the families which exhibit 
the greatest morphological resemblances to the Papilio- 
nacez, Ceesalpiniee, and Mimosee, are the Connaracee, 
Rosacez, Bignoniaceze, Saxifragaceze, Crassulacese, Passi- 
floracecee, Rhamnacez, and Thymeleaceze. In these, many 
of the genera possess indefinite and free stamens; in some 
again, the stamens are numerous as well as being free and 
indefinite. In the majority of the genera the corolla is 
regular and the petals are four or five in number. 
Many of the genera, again, possess a great development 
of pinnate, although many also have digitate, or simple, 
leaves. 
Embryological.*—The seedling leaves of all Mimosee are 
probably simply pinnate, although the leaves of the adult 
forms are bipinnate, as in Acacia, Mimosa, Cassia, Calli- 
andra, Adenanthera, Albizzia, and Pithecolobium. 
The Cesalpiniez frequently possess pinnate leaves in the 
seedling stages, but in some genera and species the seed- 
lings possess simple leaves. 
' See Appendix to this report dealing with seedling leaves, 
