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knowledge of the later fossil botany is comparatively full, — 

 wonderfully so, considering bow very recent this knowledge is, 

 — and we are in a condition to apply it hopefully and confi- 

 dently to the solution of problems which not long ago seemed 

 to be beyond the reach of proper scientific enquiry, namely, to 

 the explanation of the actual distribution of the species of 

 plants over the earth. For the main data themselves, and for 

 the clear exjiosition of them, we are most largely indebted to 

 tliree men, who hapjjily are still alive and active — Heer, 

 Lesquereux, and Saporta. 



The Linnaeus and facile princeps of tertiary botany is 

 Oswald Heer, of Ziirich, now a septuagenarian, but still in 

 harness. His " Recherches sur la Climat et la Vegetation du 

 Pays Tertiaire," rendered into French by C. T. Gaudin, was 

 published nearly twenty years ago. It is a general and com- 

 paratively untechnical presentation of a long line of investiga- 

 tions, which have since been crowned by his several memoirs 

 on arctic phyto-palasontology, now collected in the five volumes 

 of his " Flora Fossilis Arctica." All these volumes, as well as 

 others on the Swiss tertiary, have appeared within the last 

 ten years, the latest only a year ago. 



Leo Lesquereux, Heer's comjiatriot, and barely his junior, 

 came to the United States fully thirty years ago, drawn hither 

 from Neufchatel by Agassiz. The greater part of his re- 

 searches relate to the carboniferous flora, and he has recently 

 thrown interesting light upon silurian botany, as has Dawson 

 of Montreal upon the intermediate devonian. But those 

 which at present concern us relate to the cretaceous and the 

 tertiary of our own western regions. The most considerable 

 of these works are the two notable quarto volumes, entitled 

 " Contributions to the Fossil Flora of the Western Territories," 

 published by the Geological and Geographical Survey of the 

 Territories under Dr. Hayden, upon whom and whose survey 

 they reflect high credit. One volume treats of the cretaceous, 

 one of the tertiary flora. 



Any proper enumeration of authorities upon the fossil 

 botany of the later periods should include various other names, 

 and especially that of Schimper, of Strassburg, who, like 



