136 Trans. Acad. Sci. of St. Louis. 



an acute angle of divergence, ascending high up along the 

 borders and anastomosing in gentle curves. 



This leaf was membranaceous in texture, and in the speci- 

 men the margin is poorly defined. Only at one place is the 

 crenulate nature discernible. The margin near the base, 

 however, is entire. The blade was probably 8 centimeters 

 long and 5.3 centimeters broad at the widest part. The 

 petiole is wanting. The primary nerves, diverging from each 

 other at an angle of 25°-30°, are straight and strong toward 

 the base, becoming much thinner as they approach the margin 

 of the leaf. The secondary nerves are nearly parallel in 

 their course through the blade. 



On the lower side of the lateral primary nerves, gently 

 curving branches are given off which anastomose with other 

 branches near the margin. The nervilles are scarcely visible 

 and are nearly at right angles to the principal nerves. The 

 leaves of the poplar vary as to size, shape, margin and num- 

 ber of primary nerves, which accounts in great part for the 

 many species that have been ascribed to the genus. From 

 Florissant alone we have five other species, some of them also 

 representatives of the European fossil flora. 



Flores. 

 (Plate XV. figs. 1, 2.) 



While looking over the collection of fossils, two flowers 

 came to my notice, which I have not been able to classify with 

 certainty. 



Plate XV. figure 1, shows the remains of a flower that 

 seems to have affinities with some of the Onagraceae. The 

 calyx-tube prolonged beyond the ovary is 3.3 centimeters 

 long and inflated above. Its divisions cannot be made out. 

 The ovary is 1.3 centimeters long and three millimeters broad 

 at the middle. The petals, five in number, are membrana- 

 ceous, lanceolate and marked by a central nerve. The stigma 

 is cylindrical and the course of the style through the tube can 

 be traced nearly to the ovary. Most of the living Onagraceae 

 with tubular calyces are 4-merous ; a variation, however, 

 might not be improbable. 



