THE FLORA OF THE SAIA^T EUGENE SILTS 415 



pared with leaves from young shoots and saplings of the existing 

 Popiilus grandidentata Miehanx, and P. Jietero;p]iijlla Linnaeus, 

 which are frequently 3-palniately nerved. Subsequent study and 

 comparisons, however, resulted in the conclusion that the rela- 

 tion of the secondary nerves, esi:iecially the basilar ones, to the 

 midrib was more nearly comparable with the characters of the 

 lindens than with those of the poplars, and hence its present 

 reference to the genus Tilia. Definite generic identification, 

 however, from such a leaf fragment must be regarded as ten- 

 tative only. 



The base of our leaf was, apparently, rounded-cordate. The 

 midrib is stout, the marginal dentitions are fine, and the general 

 appearance is suggestive of the leaves of the existing Tilid amer- 

 icaiia Linnaeus, and T. lieterophylla Ventenat. 



Several fossil species might also be mentioned as worthy of 

 consideration, especially Tilia popidifolia Lesquereux," a Mio- 

 cene Tertiary species from Colorado, and T. speciosissima 

 Knowlton" from the Eocene of Colorado. T. dnhia (Newberry) 

 Berry {= TiliaephyUuni duhium Newberry),^" from the Pleisto- 

 cene clay of Fish House, New Jersey," is similar to ours, but is 

 not as suggestive as are the other two. The common form or 

 type of leaf is so apparent in all, however, that their generic 

 relationship can not be questioned. Leaves and fruit of T. amer- 

 icana were also listed, but without any illustration, by Penhal- 

 low,*'^ in his contribution to the Pleistocene flora of the Don Val- 

 ley, Toronto, Canada. 



Elsewhere than on the North American continent the genus 

 is also well represented in Tertiary deposits, by leaves that are, 



41 Lesquereux, Leo. U. S. Geol. Survey Terr., Kept. vol. 8 (The Cretaceous and 

 Tertiary floras), p. 179, pi. 34, flgs. 8, 9. 1883. 



*2 Kuowlton, F. H., iu Lee & Knowlton. IT. S. Geol. Survey, Prof. Paper 101 

 (Geology and paleontology of the Raton Mesa and other regions in Colorado and New 

 Mexico), p. 336, pi. 67. 1917. 



43 Newberry, J. S. U. S. Geol. Survey, Hon. vol. 26 (The flora of the Amboy 

 clays), p. 109, pi. 15, fig. 5. 1895. 



44 This deposit was originally thought to be Cretaceous in age and was included 

 in the Amboy clay series. It was subsequently determined to be of Pleistocene 

 age. A. H. 



45 Penhallow, D. P., and others, in Report of the Committee . . . appointed to 

 further investigate the flora and fauna of the Pleistocene beds in Canada. British 

 Assoc. Adv. Sei., Bristol meeting, 1898, p. 528. 



