16 MUSEUM OF COMPARATIVE ZOOLOGY. [Apr. 



Nebraska and California, have demonstrated facts, which 

 science was scarcely prepared to admit: 



First. That the floras of our ancient formations already had 

 peculiar types, which separated them from each other in the 

 different continents. This is even evident in the vegetation of 

 the Coal measure. Therefore, the supposition of a continental 

 union of Europe with America by Atlantides or other interme- 

 diate lands, is proved to be untenable. 



Second. That the essential types of the old floras, of the 

 cretaceous and tertiary formations have passed into our present 

 vegetation, or are preserved to our time. The Cretacean of 

 America, for example, has already the Magnolias, which we 

 find still more abundant in our Tertiary. This last formation 

 has furnished a number of species of the genus Magnolia, 

 nearly identical with that now existing in the United States, 

 while the genus is totally absent in the corresponding floras of 

 Europe. More than this : we find in our Tertiary the same 

 predominating types marked on both sides of the Rocky Moun- 

 tains. On the Atlantic slope, leaves of magnolias, of oaks, of 

 elms, of maples and poplars, and not a trace of coniferous 

 trees ; while in California and Vancouver Island, the red 

 woods or Sequoia, abound in the Cretacean and Tertiary, as now 

 they still form the predominant vegetation of the country. 

 These few facts are mentioned only to show the importance of 

 collections of fossil plants from every formation of our Amer- 

 ican continent, the only part of the world where questions of 

 general significance concerning palseontological distribution can 

 be studied with some chances of satisfactory conclusions. 



From our Coal measures, also, other problems of general 

 interest are still awaiting a solution. The vexed question of 

 the distribution of the vegetation at the various horizons where 

 beds of coal have been formed is one of the most important. 

 Some geologists assert that the differences in the vegetation of 

 the coal are merely due to geographical or climateric influences ; 

 while others, on the contrary, find different and essential char- 

 acters in the flora of each bed of coal. Nothing can solve 

 problems of this kind but collections of fossil plants carefully 

 made, not only in view of the determination of species and an 

 acquaintance witli the vegetation of a certain epoch, but espe- 

 cially in view of ascertaining local and general distribution 



