Kirchner — The Fossil Flora of Florissant, Colorado. 181 



the leaves described and figured by Unger. The leaves of 



5. lugubris, described by Lesquereux in the " Flora of the 

 Dakota Group," are also comparable with this leaf, but differ 

 from it in their greater size, cuneate base and scythe-shaped 

 lateral lobes. 



ACERACEAE. 



Acer. 



5. Acer Florissanti, sp. nov. (Plate XI. fig. 1). 



Leaf comparatively large, five-lobed, outline broadly oval; 

 petiole long; middle lobe longest, broad and oblong; lateral 

 lobes lanceolate ; margin incised ; base broad ; basal nerves 

 five, straight; secondary nerves distinct and nearly straight 

 to the borders; veinlets anastomose, forming a fine net-work. 



The markings of this leaf have been beautifully preserved. 

 The blade is 10.5 centimeters long and about 8 centimeters 

 broad. The middle lobe is oblong and dissected at the top. 

 Of the lateral lobes, the upper are the largest. The central 

 basal nerves, diverging at an angle of 30°-40°, are the most 

 prominent. The secondary nerves are quite straight, and 

 enter the points of the teeth on the margin. About forty- 

 six species from the Tertiary formations of Europe have been 

 described and referred to the different types of this genus, 

 whereas in this country comparatively few fossil species have 

 been found. This leaf by the facies and character of the 

 venation is comparable with the recent species, A. dasycar- 

 pu?n, which it resembles in many respects. 



6. Acer mysticum, sp. nov. (Plate XI. fig. 2). 



The specimen which is here figured represents the fruit of 

 an Acer. The fruit, oblong in shape, is nearly two centi- 

 meters long and six centimeters wide, and appears to contain 

 an ovate seed. Along the back of the wins: are four or five 

 strong nerves. These give off nervilles which are more or 

 less forked, and which cross the wing transversely nearly to 

 the margin. The wing is somewhat wider below the middle. 

 Since the seed was found by itself it cannot be safely classed 

 with any of the known species. 



