ISO E. C. Andrews — The Geological History of the 



Malpighiacese, Simarubacese, Zygophyllacese, and Meliacea), is 

 another splendid example. The Eanales form another good 

 example of this principle, Magnoliacese, AnonaceaB, and Ranun- 

 oulacese, being taken as types. The Myrtales is another good 

 example with Myrtaceae, Combretacese, Melastomacea?, Rhizo- 

 plioraeea% HaloraghaoeSB, Lythracerc, Lecythidacese, and Ona- 

 gracesa, taken as types. The Sapindacese, Aceraceae, and 

 Iiippocastanacea?, furnish another example. The catkin-bear- 

 ing families are peculiar in that they suggest an ancestry of 

 large and luxuriant trees with compound leaves dwelling in a 

 mild and moist climate, which still are large trees in the main 

 although confined for the most part to the cool and cold tem- 

 perate regions. Many families again may be divided into 

 tribes which have relations one to another somewhat similar 

 to those which the various families bear to one another in the 

 orders. Thus Papilionacese has the tribes Sophoreaa and 

 Dalbergiese, which are mainly large trees, with luxuriant pin- 

 nate leaves in warm moist regions, Gralegese and PhaseoleaB, 

 mainly trees and twining plants in warm and temperate regions, 

 while the tribes Viciese, Lotea?, and Trifolese, are mainly herbs 

 in cool temperate regions. Many other examples might be cited. 



Again, in many of the more highly organized families, there 

 is not only a tendency to become herbaceous in the colder 

 regions but also in the warmer parts of the earth. Cucur- 

 bitaceae, Lobeliacese, Campanulacea?, Compositas, Solanacese, 

 Liliacese, and Orchidacese, may be cited as examples. 



The significance of this remarkable arrangement into groups 

 as they are seen to-day appears to be that a response was made 

 to some widespread mild and moist condition of climate in the 

 far past by a great development of large luxuriant trees 

 fertilized by winds and clothed with dense foliage, the leaves 

 being pinnate, compound or toothed. Jungles were rare, but 

 great forests were common, to suit the fertilization by winds. 

 Later, as a result of another widespread climatic factor came 

 a great and rapid deployment of luxuriant trees with sym- 

 metrical flowers which began to supplant the older anemophilous 

 types. Then by the introduction of an additional factor came 

 the development of the zygomorphic corolla and the tendency 

 for such types to crowd together and to push the forest growths 

 to the less favored spots, inasmuch as the crowding and cling- 

 ing habit tended to prevent wind fertilization. Then came a 

 zoning of climates with the development of deserts in both 

 tropics and temperate regions with mild moist conditions in 

 local areas. This is suggested first, by the long-established 



