FOSSIL FLORA. 769 



The fact that Platanus leaves are very abundant in the beds surround- 

 ing the fossil trunks makes it extremely probable that the generic reference 

 is correct. It is of course also probable that some of the leaves belong to 

 the wood here described as different, but as they have never been found 

 attached, it is manifestly unsafe to assume that there was ever organic 

 union. 



A number of fossil species have been described from various parts of 

 the world; none, however, from North America, The general agreement 

 between these and the one under consideration is close, but the specific 

 differences are marked in certain cases. One of the nearest forms is 

 Platanus Jdebsii Casp., 1 from the Tertiary of Prussia. It differs in important 

 minor characters, as does P. borealis Casp., 2 from the same place. The two 

 species described by Felix, Plataninium porosum Felix and P. regulare 

 Felix, have only general resemblance. 



In the original MS., which was submitted in March, 1896, I had of 

 course given this another specific name, and it may still prove to be different 

 from the P. hay dent of Felix. Unfortunately Felix has not figured his 

 species, and it is difficult, from a mere technical description, to be entirely 

 certain of their identity. It is reasonably certain, however, that they are 

 identical, and I have so regarded them. 



Habitat: Specimen Ridge Forest, near head of Crystal Creek, Yellow- 

 stone National Park. From a trunk 6 inches in diameter and about 1 foot 

 in height; collected by F. H. Knowlton, August 25, 1887. 



Rhajinacinium kadiatum Felix. 



PI. CXVIII, figs. 6, 7; PI. CXIX, fig. 1. 



Rhamnaciniumradiatum Felix: Untersucbung fiber fossileHolzer: Zeitschr. d. Deutsch. 

 geol. (resell., Jahr. 180G, p. 252, PI. VI, fig. 3, 1S96. 



Transverse section. — Amui;i] ring broad (7 mm.), very indistinct, consisting 

 of only 1 or l' rows of slightly thickened wood cells and rather abrupt 

 presence of numerous large ducts in succeeding spring wood. Ducts very 

 numerous, in radial rows. A few of the ducts are single, but mainly they 

 are contiguous, with 2 to 10 in a, series. The usual number is 3 or 



'Einige foss. Hiil/.er Preassona : Abhandl. ■/.. geol. Speoialk. v. Preussen u. Thiiringischen 

 Staaten, L889, PI. VIII, figs. 1-24. 

 op. oil,, PI. IX, figs. 1-11. 

 WON XXXII, PT II 49 



