362 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



groups of apparently exotic plants that are met with are 

 only to be explained as the residue of secondary elements. 

 Examples of the extent to which the composite character of 

 the tertiary flora has still been retained are found in Japan, 

 the southern portions of North America, and California, where 

 plants related to those of almost all other regions occur. He 

 sums up his conclusions as follows : 1. The natural floras of 

 the world are allied to each other by the elements of the 

 tertiary flora. 2. The character of a natural flora is deter- 

 mined by the predominant development of one floral element 

 (the principal element). 3. Secondary elements have also af- 

 fected the composition of modern floras, according to cli- 

 matic conditions. The intermixture of members of the vege- 

 table kingdom, apparently foreign to the character of the 

 flora, produced in this way, sometimes appears only subor- 

 dinate, but at others is of such an extent that it decidedly 

 affects the character of the flora. 4. The species replacing 

 each other in the regions of the different modern floras are 

 corresponding members of similar elements. 19 C, November 

 14,1874,429. 



CATALOGUE OF THE FLOKA OF NEBRASKA. 



A catalogue of the flora of Nebraska, by Professor Samuel 

 Aughey, has been published by the University of Nebraska, 

 with special reference to making exchanges of specimens. 

 The general arrangement corresjDonds to that of Professor 

 Gray, in his botanical works, and includes 2034 species as 

 having been actually observed. Professor Aughey remarks 

 that many of the native species along the eastern border of 

 the state are rapidly disappearing, and others taking their 

 place. Thus eight years ago the " silver-weed," Potentilla 

 anserina, was common along the Missouri from Omaha to 

 Dakota City, but is now rarely met with. He thinks, there- 

 fore, that the present condition of the flora of Nebraska 

 should be put on record, so as to mark with greater accuracy 

 the changes that may take place from year to year. 



VEGETATION OF AMSTERDAM AND ST. PATTIES ISLANDS. 



It is a curious fact that the little island of Amsterdam, in 

 the South Indian Ocean, is known to be covered with trees, 

 while that of St. Paul's, only fifty miles to the south, is des- 



