290 FLORA OF LOWER COAL MEASURES OF MISSOURI. 



contemporaneous beds and the top of tlie Lower Carboniferous in the Wyo- 

 ming Valley, are represented by an imcoirformability in poi-tions of Missouri. 

 But very little is known of the plants of the Lower Coal Measures 

 south of the Kentuckv-West Virginia boundary. But extensive material, 

 showing a rich and highly varied flora, has been collected from the Kana- 

 wha series, about 1,200 feet in thickness, along the Great Kanawha River, 

 in the latter State. Although these collections will properly form the sub- 

 ject of a special report, it may be remarked in this place that few of the spe- 

 cies tabulated above are met with below the middle of the Kanawha series, 

 while many common species, such as Annularia splienophylloides or Neurop- 

 teris Scheuchzeri, are found only in the upper third of that series. In fact, the 

 paleontologic features of the Kanawha series are more nearly like those of 

 the Lower Coal Measures of Europe, as will in due time be shown. 



TEMPORARY OBSTACLES TO ACCURACY IN CORRELATION. 



Far more serious than all the natural limitations of fossil plants as a 

 means for geologic correlation in our American Carboniferous terranes is 

 the difficult}" resulting from the lack of standard paleobotanic sections for 

 comparison. B}- jjaleobotanic section is here meant a knowledge of tlie 

 plants that may be found in all the various phytiferous beds that comprise 

 or may with assured accuracy be referred to a single section. Such sections 

 would become, according to their completeness, with reference to the num- 

 ber or neaniess of the fossiliferous beds and the degree of exploitation of 

 the floras, their extent, or their geographic and geologic positions, standards 

 not only for the comparison and reference of isolated beds or plant-bearing 

 horizons in the same vicinity or region, but for the determination of time 

 equivalents in diiferent fields or basins. 



The surprising and painful inadequacy of the materials relating to 

 stratigraphic paleobotany, which has been referred to in the above discus- 

 sion of the distribution of the Missouri plants, and which constituted so 

 serious an obstacle in the attempt to ascertain the age of the outlying small 

 basins in southwestern Missouri, has already been set forth in another place.^ 



'Bull. U. S. Geol. Survey, No. 98, 1893, pp. 118-120. Tho conclusion that in these basins coals 

 were probably formed ue.ir the close of the time of No. XIII, or during the deposition of the Lower 

 Barren Measures, No. XIV, reached in the report on these basins, h.as, so far, been supported by sub- 

 sequent studies of the plants in other fields. Several of the peculiar forms then described have since 

 been met in the McAlester coal field of Indian Territorv. 



