Gress: Fossil Plants of the Dakota. 291 



preserved. The venation shows marked similarity to our modern 

 Bctula. The great difficulty met with in classifying these leaves is to 

 distinguish one variety of Bctulitcs Westii from some one or from 

 several of the other fourteen varieties, which Lesquereux has, I be- 

 lieve unnecessarily, recognized in this species. A distinguishing char- 

 acteristic of Bctulitcs IVcstii is the long, slender petiole, which unfor- 

 tunately is absent in nearly all of our specimens. The bifid stipule, 

 with lanceolate pointed lobes, which Lesquereux says is rarely pre- 

 served, is also lacking, another mark of distinction. I have found 

 also a close similarity between some of the Bctulitcs and the Vi- 

 burnums, as figured in the Flora of the Dakota Group, such, for ex- 

 ample, as Bctulitcs popidifolius and Viburnum Lcsqucrcnxii var. 

 cordi folium. One specimen, which seemed to fit each genus equally 

 well, was referred to Bctulitcs on account of the glandular tipped 

 teeth, wliich seemed to be more characteristic of our modern Bctula 

 than of our Viburnums. 



9. Betulites populifolius Lesquereux. 



Betiilites populifolitis Lesquereux, The Flora of the Dakota Group, U. S. 

 Geological Survey, Monograph XVII, 1892, p. 64, PI. 6, figs, i, 2. 



Description: The leaf is 6 cm. long and about the same width at 

 a distance of 2 cm. from the base. The base is somewhat truncate- 

 cuneate and the apex is obtusely pointed. The margin is distinctly 

 dentate. The midrib is straight and thick. There are about ten pairs 

 of secondaries, which are oblique, parallel, equidistant, and alternate, 

 except the lowermost pair, which is opposite. Each secondary passes 

 straight to a tooth in the margin. About two-thirds of the distance 

 from the midrib each secondary sends off a branch from the lower 

 side, which passes to a tooth in the margin. Only a portion of the 

 petiole is present. There are four specimens, which I have referred 

 to this species. Nos. 9 and ga are parts of the same nodule and are 

 therefore upper aiid lower surfaces of the same leaf. Nos. gb and 

 gc also show the upper and lower surfaces of another leaf. One 

 specimen (gb) shows glandular-tipped leaves. This is true of our 

 modern Bctula populifolia. These leaves resemble some of our mod- 

 ern Viburnums. While some of our Viburnums show callous-tipped 

 teeth, I have found none to show the glandular tips. This fact has 

 influenced me in referring these leaves to Bctulitcs. 



