Fossi/ I^ of any. 21 



the last links connecting- the fern floras of the two extremes, east 

 and west, and showing the snccession of types connecting the 

 present with the past. Geology teaches us that at various times 

 in the world's history, the floras of regions of greater or less 

 extent have, from various causes, been destroyed ; for example : 

 Toward the latter part of the Tertiary period, the flora of a large 

 portion of Central California was annihilated by extensive volcanic 

 eruptions, which covered the surface with ashes and molten lava. 

 Fossil remains of trees and plants of that period have been found 

 in deposits under the lava; some of these have been determined 

 as belonging to genera, quite different from those now found 

 living in California, and most resembling plants of the later Eu- 

 ropean Tertiary species 



These fossil plants are specially interesting to pake(^ntologists 

 and ethnologists. To the palaeontologist, because animal life is 

 preceded and explained by vegetable life. To the ethnologist 

 from the plants having been found in deposits containing human 

 bones and other evidences of man's occupancy of the region, at 

 and previous to the time of the volcanic eruption. (See my arti- 

 cle on 'Pre- historic California,' read before the California Histor- 

 ical Society, January, 1888) 



After a lapse of time necessary to form new soil and restore 

 atmospheric conditions favorable to plant life, the places of the 

 plants destroyed were, either by plant migration, natural distribu- 

 tion, or by evolution, subsequently occupied by other and dif- 

 ferent species. 



Whether the succession of species was due to the gradual 

 changes and modifications of earlier forms, or to the spontaneous 

 generation or production of new forms, is a cjuestion upon which 

 there is great diversity of opinion among men who have been 

 close students of nature. 



A notable instance of this character in England is that of the 

 Isle of Sheppey, at the mouth of the Thames, where large quan- 

 tities of fossil remains of fruits, tropical plants, fishes, turtles, 

 shells, etc. are continually washed out on the sea coast. Among 

 them large numbers of fruits of palms closely allied to the Nipa 

 Palms of the Moluccas and Philippines. 



The character and position of the numerous marine and fresh 

 water genera, in the eocene clay, show that this celebrated fossil 

 deposit was formed in the delta of an immense river of eocene 

 times, which probably flowed from near the Equator toward the 

 spot where these interesting remains are now so abundant. This 

 river was lined along its banks by magnificent tropical vegetation, 

 and the country inhabited by curious birds, reptiles and mam- 

 mals, while the waters teemed with sharks and fishes. 



Among the most interesting fossils of the writer's collection are 

 fine specimens of the fruits and seeds of eocene palms from this 

 locality. 



In 1840, Mr. J. S. Bowerbanks published a work on the ' Fos- 



