214 The West American Scientist. 



been removed by denudation and detrition, overlie the Cretaceous 

 and others of the olden rock formations. 



While the extensive fresh-water sedimentary deposits in which 

 the fossil plants and insects are found in great abundance, and the 

 large quantities of fossil bones of distinct mammalians, and the 

 shells of MoUusks, show that the continents and islands of the 

 period were intersected by extensive lakes and inland seas, marine 

 bays, and arms of the sea penetrating deeply into the land ; and 

 especially during the Eocene or older tertiary, Hakeas, Mimosas, 

 Palms and many other interesting trees and plants grew in great 

 abundance in the then tropical atmosphere of the present temper- 

 ate and frigid zones. 



From the Miocene plant beds of Greenland, one hundred and 

 thirty-seven species of fossil plants have been described or identi- 

 fied, including among a large number of trees of the temperate 

 zone, species of Magnolias, Limes, Walnuts, etc.; their fruits and 

 seeds in various stages of development are found with them, show- 

 ing that they grew where they are found, and this to within eight 

 degrees, fifteen minutes, of the North Pole, where darkness now 

 reigns during six months of the year, and where the country is 

 continuously covered with ice and snow. 



During this period the vegetation flourished, and their remains 

 were deposited in the estuaries of the rivers, forming the coal 

 which is now being mined on this coast, supplying us with fuel 

 wherewith to cook the vegetable products of our own time. 



Among the trees of the period under consideration, whose fossil 

 remains have been discovered and determined, are numerous 

 Conifers, Eucalyptus, Mimosa, Olive, Diospyros, Ailantus, Ficus, 

 Almond, Cinnamon, Salisburia. Aralias, Anona or Custard Apple, 

 Sterculia, Oreodoxites (resembling the Oreodoxia regia or Royal 

 Palm of South America.) and many other Palms; Melons, Gourds, 

 and many trees and plants resembling those with which we are 

 familiar. 



Among ferns are extinct species of Osmundo. Pteris, Gymnog- 

 ramme, Lastrae, Diplazium and Lygodium, besides the extinct 

 genera Andiantites and Sphenopteris. 



The most beautiful fosssil leat beds belong to the Upper Mio- 

 cene, in the valley ol the Rhine. 



They were explored by Professor Heer, who published a large 

 and valuable work on the subject. In this deposit the record is 

 so complete, that distinct sprays of a kind of camphor tree are 

 found with flowers, fruits and leaves; on some remains leaf fungi 

 can be detected, and the season of the year when certain portions 

 of the deposits were made, can often be inferred from the plants 

 being in their spring or autumn state of growth. 



In that locality, about one hundred and eighty species have 

 been identified, among them seven kinds of Palms; the ierns are 

 precisely the same as our recent ones, but of a sub-tropical type. 



