23 1 DESCRIPTION OF SPECIES. 



These are sufficient to identify the leaves; fig. 2 being similar to pi. xxii, 

 fig. 3, and xxiii. fig. 4, of Heer, and fig. 9 to pi. xxiii, fig. 7. This last leaf 

 has Hie base Iruncate not cordate, but this form is marked also in the last 

 figure quoted from Heer and in fig. 8 of pi. xxiii; therefore this difference 

 cannot eliminate the essential points of identification. I am the more 

 disposed to consider these fragments as representing Heer*s species, that 

 very fine entirely preserved leaves of this maple have been obtained by 

 Professor Whitney from the Chalk bluffs of California, and described in 

 "Appendix to the Fossil Plants of the Auriferous gravel deposits'' (Mem- 

 of the Mus. Comp. Zool. at Harvard College). 

 Hah. — Bad Lands. Professor Wm. Denton. 



.Acer gracilescens, sp. nov. 



Plate XLIX, Fig. 7 (6?). 



Leaf small, coriaceous, loug-petioled, palmately three-lobed ; lateral lobes short, 

 oblique, lanceolate, obtuse, the terminal much longer, all entire; base broadly cuneate, 

 obtusely once-dentate on both sides below the lobes. 



The leaf is about 4 centimeters long, the medial lobe being broken 

 below the top; 2i centimeters between the lateral lobes, and the flexuous 

 petiole is a little more than 2 centimeters. There is a short obtuse tooth 

 on each side above the cuneate base, and hence the leaf is enlarged to the 

 points of the lateral lobes and lanceolate to the apex. I find nothing to 

 which this leaf might be compared. It has somewhat the facies of the 

 small leaves of Acer Bolanderi, Lesqx., "Aurif. grav. Deposits," in "Mus. 

 Comp. Zool. of Harvard," vol. vi, No. 2, but it is more slender in all 

 its parts; the lateral lobes are narrow and entire. The nervation and 

 areolation are normal. 



Though the difference in the characters appears very great, I am dis- 

 posed to regard fig. 6 as representing a variety, or rather a deformation, 

 of the normal form of this species. The leaf is three-lobate in the upper 

 part and narrowed toward the petiole, where it is abruptly rounded; it has 

 two opposite, short, entire, obtusely pointed lobes, as in the normal leaf, 

 fig. 7, placed much higher, and the nervation is pinnate on account of the 

 difference of position of the lobes, the lateral nerves being parallel, equi- 

 distant, all on the same acute angle of divergence. A modification some- 



