DESCRIPTION OF SPECIES— ACERACE^ 261 



Fl., p. 56, pi. ii, figs. 1-3; pi. xxiv, fig. 2; pi. xxix, fig. 8), and which, accord- 

 ing to European authors, migh.t rather represent some kind of Aralia. In 

 the same work, I liave described as Negundoides a fragment of a leaf whose 

 attribution is very doubtful; and from the Cretaceous of Niedershoena, d'Et- 

 tingshausen has an Acer antiquus, which he considers himself as of uncertain 

 generic reference. Hence we have no positive evidence of the presence of 

 Acer, nor of any Aceracece, in the Cretaceous; and the absence of plants 

 of this order in the Eocene of Europe and of America confirms the non- 

 existence of tliis group in the Cretaceous and the Lower Tertiary. The 

 oldest representative of ^cer appears in the Armissan of France, where it is 

 extremely rare; the genus becomes more predominant in the Lower Miocene, 

 and has its largest preponderance in the Middle and Upper Miocene. In 

 North America, as remarked above, we know only two Miocene species, one 

 from Carbon, the other from Alaska. Other kinds of Aceracece, Sapindus and 

 Ncgundo, have also representatives in the same formation. They become, 

 however, more numerous in more recent stages of the Tertiary; for the Upper 

 Green River group abounds in leaves of Sapindus ; it has, besides, one species 

 of Acer, identified in the Pliocene of California, which has two kinds of Maple 

 leaves in the fifty species known from this group. It is very probable that 

 Acer will be found amply represented in the Pliocene of the Mississippi River. 

 Acer Irilobatuin var. p r o d u c t n lu 2 , Al. Br. 

 Plate XLVm, Figs. 2, 3«. 



Acer trilohatum, Al. Br., N. Jahrb. v. Broun & Leouh., 1845, p. 172.— Ung., Cblor. Prolog., p. 130, pi. xli, 

 figs. 1-8.— Heer, Fl. Tert. Helv., i,p. 48,pl. ii, figs. 3,4,6,8; iii, p. 47, pi. cs, figs. 16-21 ; cxi, 

 figs. 1, 2, 5-14, 16, 18-^21 ; cxii, figs. 1-8, 11-16 ; csiii ; cxiv ; cxv ; cxvi, figs. 1-3 ; p. 197, pi. civ, 

 figs. 9, 10.— Ung., Foss. Fl. v. Kumi, p. 49, pi. xii, figs, 28-30 —Sap., fit., iii, p. 101.— Lndw., 

 Palajont., viii, p. 127, pi. 1, figs. 1-5 ; Ii, figs. 4-11 ; Iii, figs. 2, 4-7 ; liii, fig. 6.— O. Web., Pa- 

 leont., ii, p. 19.5.— Ett., Foss. Fl. y. Bil., iii, p. 18, pi. i, fig. 14; xliv, fig8.1-.5, 7-9, 12-15.— 

 Lesrix., Annual Report, 1872, p. 388; 1873, p. 408. 



rinjUilcs Mlohattis, Stcrnb., Fl. d. Urw., i, p. 42, pi. 1, fig. 2. 



rhijUUi-8 lobatus, Sternb., ibid., p. 39, pi. xxxv, fig. 2. 



Acer irictispidatiim, Al. Br., I. c, p. 172. 



Acer patens, Al. Br., Stizenb. Verz.. p. 84, 



Acer prodiwtiim, Al. Br., N. Jabrb., I. c, p. 172.— Ung., Cblor. Protog., p. 131, pi. xli, figs. 1-9 ; Stizenb. 

 Verz., p. 84. 



Acer rilifoVuim, Ung., Chlor. Protog., p. 133, pi. xliii, fig. 10?. 



Acer megalopterix, Ung., Sillog., iii, p. 47, pi. xv, fig. 6. 



Acerites fdicifoliiis, Viv., M6m. Soc. Gi5ol. do Fr., 1833, i, p. 131, pi. ix, fig. 5 ?. 



Aceritcs dejierdiliis, Mass., Fl. Foss. d'ltLl. Mer., p. 4, pi. ii, fig. 7. 



Liquidambar ScaraMliaiium el L. ajjiiie, Mass., Fl. Foss. Senog., pi. ii, fig. 1 ; pi. iii, fig. 5. 



Flataniis cnneifolia, Goepp., Scboss. Fl., pi. xii, fig. 1. 



Leaf comp.iratively large, deeply trilobate, narrowed to a long petiole; lobes sharply acuminate, 

 the middle twice as long as the lateral ores; borders dentate. Fruits small ; nutlt ts obovate; wings 

 oblong, obtuse. 



The characters of tlii.s leaf, the only one satisilictoiily pr''served from 



