THE LITTLE MISSOURI BAD LANDS. 



637 



bits of carbonized wood, twigs, and bark, leaves no doubt as to the 

 character of the primal vegetation. 



But it is in the beds immediately associated with the coal that we 

 find the most indubitable evidence at once of the presence and charac- 

 ter of the former flora. Here, in strata of sand and clay, lie most 

 beautiful impressions of the leaves of both deciduous and coniferous 

 trees. We may say fossil leaves, but this is hardly the correct de- 

 scription, since we have preserved to us not a vestige of the original 

 leaf, but simply a mold left in the imbedding clay, as the matter of 

 the leaf disappeared. In fortunate cases, therefore, we have both the 

 upper and lower surfaces of the leaf exhibited, and these impressions 

 are perfect, so that experienced observers can determine, not the order 

 only, but the genus, often the very species and variety, of the tree 

 from which a given leaf has fallen ! This seems astonishing to the 



Fig. 5. Juglans woodiana (Heer). 



Fig. 6. Corilus grandifolia (Newberry). 



ordinary student or analyst of flowers, or to him who notes the great 

 variety of form and feature which the leaves of a single tree present 

 a box-elder, for instance but fails to see the hidden lines -which be- 

 tray relationship. But such men as Goeppert, Heer, Saporta, and our 

 own Lesquereux, like Tischendorf among the MSS., have a vision and 

 an experience not possessed by many, a " special insight," Professor 

 Lesquereux says, which, in presence of a single organ, a single leaf, 



