26 FOSSIL FLORA OF THE SIERRA NEVADA. 



ACERINEiE, 



ACER, Linn. 



Acer eequidentatum, sp. nov. 1 



PI. VII Figs. 4, 5. 



Leaves small, tripalmately lobed; lateral lobes short, placed above the middle of the leaves, 

 abruptly pointed; borders acutely dentate, rounded at the base, or truncate to a 

 long sit ndi r petiole. 



The substance of these leaves is rather thick, and their size apparently 

 small, the largest one seen from all the specimens being about eight cen- 

 timeters both ways. The borders are cut all around by acute equal teeth 

 turned upwards somewhat like those of Platanus, and all are entered by 

 the primary and secondary nerves ; the fibrillae are comparatively thick, 

 continuous; the middle lobe is twice as long as the lateral ones, lanceolate- 

 pointed. The relation of this species is distinctly marked with A. viti- 

 folium, Al. Br., represented in Flor. Tert. Helv., III. PI. CXVII. Fig. 14, 

 which, by its outline, short lobes, and long slender petiole, is of the same 

 characters as those figured here, merely differing by shorter teeth, and 

 still shorter, more obtuse lobes. It is still, by its form and denticulation, 

 more like the leaf of Weber, Pakeont. (separ. abd.), p. 83, PI. V. Fig. 4 b, 

 referred to A. vitifolium by the author, and by Heer to his A. brachyphyl- 

 lum, which has a five palmate nervation, and is therefore of a different 

 type. The borders of the leaf of A. vilifoUum have not been observed by 

 Heer, and the characters of the teeth are not yet positively recognized. 

 Professors Al. Braun and Ettingshausen, the last in his Bilin flora, have 

 described the species without figures, the teeth being indicated as obso- 

 lete. The type is that of our present Acer spicatum, Lam., whose leaves, 

 some of them, at least, have the general outline of the fossil ones, the 

 truncate base, and the long slender petiole. Its teeth, however, are 

 longer, mostly double and irregular, and the lobes acuminate. 



Hubitat. — Chalk Bluff's, Nevada County, California. Voy's Collection. 



1 Acer vitifolium is written upon the plate by mistake. 



