262 UNITED STATES GEOLOGICAL SURVEY— TERTIARY FLORA. 



many spcciiiKMis observed at I lie same locality, are somewhat different from 

 tliose which have been referred to this species I)y European authors, and of" 

 which numerous specimens have been figured; for it is one of the species 

 the most commonly found in the Middle Miocene of Switzerland, Germany, 

 and Italy. It differs especially by the more acuminate and more oblique 

 lateral lobes, and by the more equal and shorter teeth. There are, however, 

 corresponding forms for tiie length and obliquity of the lobes represented in 

 Heer for examjile (loc. cit., pi. cxii, tigs. C, 7), this last, a leaf with borders 

 equally and short dentate, as they are seen iu tig. 2 of our plate. A. tri- 

 lobatum-produduvi in pl.cxiv, fig. 8, and pi. cxv, figs. 8, 11, of the same author, 

 has the leaves with the narrowed base and the prolonged middle lobe, the 

 borders, however, more deeply and irregularly dentate; and Ludwig also 

 (Joe. cit., pi. 1, fig. 3) represents a leaf of an analogous form, l)ut which lias at 

 its base two lateral veins, wanting in that of our fig. 2, which is exactly three- 

 nerved, like most of those referred by Heer to this variety. I am, therefore, 

 disposed to consider the specimen from Carbon as referable to the same 

 species. I have, moreover, seen fragments with a more definite denticulation, 

 and all were found at the same locality. The seeds also (fig. 2(/) are differ 

 ent, especially by the small size of the wings, directed straight upward, and 

 of the nutlet, rather truncate at the point of insertion of the wings, from those 

 which have been referred to this species by European authors. Tlic otdy 

 fruit of Acer, however, corresponding in characters with those which are 

 figured upon our plate, is that in Heer {loc. cit., fig. 16/>), the upper one of 

 the same size as ours, the wing scarcely more inclined, and the lower one 

 larger, but both considered by the celebrated author as fruits of A. trdohatvm. 

 Further researches at Carbon, where the fragments of leaves oi Acer are not 

 rare, may result in the discovery of specimens more definite in characters as 

 evidence of their specific relations. 

 Habitat. — Carbon, Wyoming. 



Acer tc q u I d c n t a t II Ml , Lesqx. (ined .}. 



PlatoXLVIII, Figs. 1,,-!. 



Leaves small, trilobate, and palocately three-nervdl ; liitcral iDben Bbort, oblique, acute; borders 

 equally distantly denticulate. 



Some well-preserved leaves have been described under this name in the 

 Fh)ra of the Gohl Gravels of C.alifi)rnin, which is not yet published, and I 

 consider these figured here as referable to the same species. These leaves 



