224 GEOLOGY OF THE DENVER BASIN. 



The explanation of all this early laxity in the records concerning the 

 localities and geologic horizons from which so many fossil plants were 

 obtained is apparently twofold. No doubt the prime cause of the trouble 



is to be found in the conditions of the reconnaissance work during which 

 the early collections were made. A flood of new material from various 

 collectors, in many different localities, was poured upon the paleobotanist 

 each year, and he was expected to determine the species and correlate the 

 formations at once. The recording of locality and horizon, even when 

 known, was to a great extent impossible without the aid of a large clerical 

 force. But it is also (dear that the necessity of such a record was not duly 

 appreciated either by geologist or paleontologist. Both placed a value upon 

 fossils, a large proportion of which were new to science, which could 

 legitimately he given to them only by a series of accurate observations, 

 accurately recorded. 



Present knowledge of the fossil plants In Chapter VII Mr. Kllowltoll States 



the extent of the revision of the Laramie and allied floras which has 

 been attempted, and gives in summary form the result for the formations 

 of the Denver Basin. Owing to the vast amount of material to he 

 examined and the necessity for new collections and observations in some 

 important localities, this revision is still far from complete, lint as regards 

 Colorado, where the stratigraphic relations of the plant-bearing horizons 

 are best known, the revision is most advanced and the results most 

 satisfactory. 



The Denver flora, as at present known, embraces 150 species, the 

 Laramie flora of this district contains 98 species, and but 15 species are 

 common to both formations. For this district, then, the floras are very 

 markedly distinct. 



If the entire known Laramie flora of Colorado, embracing large col- 

 lections from the coal fields of Canyon, Walsenburg, Baton, and the 

 West Elk Mountains, be compared with the Denver flora, it is found that 

 out of more than 100 species in the Laramie of Colorado only a very few 

 have been found in the Denver beds. Further comparisons, as with the 

 Laramie floras reported from Wyoming and farther north, are as yet 

 impracticable. 



