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



siliceous sands and rocks of Australia, whose seedling stages 

 also proclaim their recent derivation from forms very differ- 

 ent to their present ones — how are the facts named to he recon- 

 ciled with the statement by paleobotanists that they formerly 

 existed as luxuriant types in the mild and moist climate of the 

 Cretaceous and Eocene? It is not that Australian botanists 

 would deny the existence of Myrtaceae, Proteaceae, and allied 

 families in Europe, during Cretaceous and Tertiary time ; 

 what they would deny, however, is that the endemic genera 

 of Australasia ever did form a part of the Cretaceous and 

 Tertiary flora of the Northern Hemisphere. This is the first 

 portion of the problem to be approached. 



Other portions of the problem deal with the hypothecated 

 land connections between Australia and South Africa, South 

 America, New Zealand, and the Northern Hemisphere, 

 respectively. 



Thus the Proteaceae, and the Eestiacese, are practically con- 

 fined to Australia and South Africa, while certain genera 

 such as Helichrysum, Helipterum, and Cassinia, in Composite. 

 Bulbine, Wurmbea, and Cassia in Liliaceae, are almost confined 

 to these two countries. 



In Southern South America and Australia, there are many 

 genera and species confined almost entirely to the two areas. 

 New Zealand and Australasia show even greater affinities, 

 while striking similarities exist between the floras of Australasia 

 and those of the great temperate areas of the Northern Hemi- 

 sphere especially in the families Ranunculaceae, Ceraniacese, 

 Stellatae (Lindley), Composite, Cruciferae, Lobeliacese, Umbel- 

 liferse, and Boraginaceas. 



There is also the interesting problem to be faced of the 

 evident closer connection, in former times, between the western 

 and eastern Australian floras. 



One of the most interesting of the questions raised also 

 by this knowledge of the broader relations of the Australian 

 plant types to the generalized types of the tropics and of 

 the world at large is that which is connected with the xerophytic 

 forms such as Acacia, many Cassias, Senecio, Lobelia, and 

 others. These forms apparently were world-wide in their dis- 

 tribution before the isolation of Australia from the rest of 

 the world, and they are xerophytic types in nearly every 

 country. Do they connote deserts existent with the supposed 

 mild and moist climate during the cosmopolitan distribution 

 in the Cretaceous and the Eocene ; do they imply the existence 

 of a differentiation of climate at the close of the Cretaceous ; 



