DESCRIPTION OF SPECIES— PLATANE^. 181 



nerves, numerous, equidistant, parallel, on the same open angle of divergence 

 of 60°, obliquely crossed by very strong nervilles, are common characters 

 to all the specimens of this species. From the position of the lower lateral 

 nerves in our fig. 1, they appear opposite from the base of the leaf, and 

 show a tripalmate nervation. In fig. 2, the lower nerves are alternate, a dis- 

 tribution which, tliough rare in leaves of Popvlus, is seen, as observed 

 above, in the living P. balsamifera, var. angustifolia. Therefore, as the con- 

 sistence of this leaf and its shape are the same as in that of fig. 1, I consider 

 it as representing the same species. This Populus is very closely allied to 

 P. Gaudini (F. 0.), Heer (Fl. Tert. Helv., pi. Ixiv), by the form, the size, and 

 the borders of the leaves entire or undulate. The nervation is also of the 

 same type, rendered still more analogous by the absence of one of the pri- 

 mary nerves in Heer's fig. 6, as it is in fig. 2 of our plate. The European P. 

 Gaudini differs by the midrib being nearly half narrower, and the leaves 

 abruptly narrowed into a long acumen. 



Habitat. — Raton Mountains, base of Fischer Peak, New Mexico {Dr. 

 F. V. Hayden). I found the small leaf of fig. 2 at the same locality. 



PLATAN E^. 



PLATANUS, Toiu-. 



Four species only of this genus are known at our epoch. Platanus 

 occidentalism Linn., the Plane-tree, or Buttonwood, as it is generally called, is 

 common in this country, and one of the largest trees of the North American 

 continent. Its habitat, by predilection, is along the rivers of the rich bottom- 

 land fertilized by inundations, where it attains sucli a size that its trunk 

 measures sometime four feet in diameter, even more, its branches spreading 

 wide around in a kind of wild, irregular fashion peculiar to it, denoting free- 

 dom of movement, and strength rather than elegance. Like the pioneer of the 

 western wilderness, it seems uncouth and coarse. Its white bark hangs in 

 patches along its branches, like the shreds of an old tattered garment, but its 

 limbs are sound and healthy, always covered in summer with a profusion of 

 large leaves. Its trunk is often hollow, but the tree is tenacious of life. It 

 defies the attacks of the wild elements, the devastating hurricane, the cold 

 storms of the winter, the tropical heat of the hottest summer days, protecting 

 against the multiple changes of our capricious climate the world of vegetables 



