180 DESCRIPTION OF SPECIES. 



lateral primary nerves being much stronger than the secondary; but all the 

 nerves and their divisions are craspedodrome; the nervation is positively 

 that of a Tilia. In fig. 9 the primary nerves, though more distant, are not 

 stronger, and the teeth of the borders are triangular, somewhat unequal, 

 not turned up as in fig. 8, except toward the base, where they have 

 evidently the same character in both leaves. The teeth are very variable 

 on the borders of the leaves of Tilia, even on those of the same tree, and 

 the habitat being the same I refer these to the same species. 

 Hob. — Florissant. Princeton Museum, Nos. 886 and 887. 



ACEEACE^. 



ACER, Linn. 

 " U. S. Geol. Kep.," vii, p. 260. 



Acer fequideiitatum, Lesqx. 



Ibid., p. 262, pi. xlviii, figs. 1-3. 



Acer i u d i t i s u in , ep. nov. 



Plate XXXVI, Figs. 6,9. 



Leaves small, of thiu texture, round-truncate in outline, five-nerved aud five- 

 lobed ; lobes entire, sharply acuminate; sinuses broad, entire or dentate in the middle ; 

 petiole comparatively long, inflated under the point of attachment. 



The leaves are 5i centimeters broad between the points of the upper 

 lobes and only 4 centimeters long from the top of the petiole, which is 5J 

 centimeters long. They are truncate at base, the lower lobes shorter, 

 turned outside at right angles to the medial nerve ; the upper lateral ones 

 a little longer, also turned outside. The primary nerves are thin; no trace 

 of secondary nervation is seen. 



This species is comparable to Acer Sibiricum, Heer, "Fl. Foss. Arct.," 

 v, p. 46, pi. x, figs. 45, 5a, -55; xi, fig. 2, differing by the base of the leaves 

 being truncate and entire, not dentate, the sharply acuminate longer 

 lobes, the terminal also entire, the medial nerve being simple like the 

 lateral ones, without branches going to the borders. The affinity of this 

 leaf is more evidently marked with Acer rubrum, to which the fruit, fig. 9, 

 is still more intimately related. 



Hab.— Randolph Co., Wyoming. U. S. Geol. Expl. Dr. F. V. Hayden. 



