7^ FOSSIL FLORA OF THE JOHN DAY BASIN, OREGON, [bxtix. .'Of. 



smallest example was apparently al)()ut s cm. long- and is a little over 

 4 cm. wide. 



Locality. — Mascall l)eds. Van Horn's ranch, about 12 miles west of 

 Mount Vernon, Grant County, Oregon. Collected by Merriam and 

 Knowlton, July, iJ)01 (U. S. Nat. Mus., No. 8578). 



Family ACERACP]^. 



Acer Osmonti n. sp'. 

 PI. XIII, fig. 3. 



Leaf membranaceous, five-lobed from the top of the petiole, lower 

 pair of lobes small, at right angles to the midrib, other pair large, at 

 an angle of 45° with the midrib; central lobe evidently largest of all 

 (mainly destroyed); all lobes irregularly toothed and lobed, the lobes 

 sharp pointed; petiole very long and strong; nervation palmately 

 five-ribbed, the ribs ending in the main lobes, each with several pairs 

 of alternate secondaries which emerge at an acute angle and terminate 

 in the teeth of small lateral lobes; nervilles numerous, rather thin, 

 mainl}" percurrent and crossing approximately at right angles to the 

 secondaries; finer nervation producing rather large areola?. 



The genus Acer seems to be quite rare in the Bridge Creek l)eds, 

 although abundantly represented in the Mascall beds at Van Horn's 

 ranch and vicinity. All that I have thus far seen is the leaf here 

 described, a fragment of another, and less than half a dozen fruits. 

 The one under consideration lacks the major portion of the central 

 lobe and the terminal portion of one of the large lateral lobes. It 

 spreads about 8 cm. between the points of the lower lobes and about 

 11 cm. between the points of the larger lobes. The length of the leaf 

 can not be determined, but it can hardly have been less than 9 or 10 cm. 

 The petiole, very thick and stout for the size of the blade, has 4 cm. 

 of its length retained and was evidently somewhat longer. 



This leaf has a very modern appearance, much more so, in fact, 

 than the forms found in the Mascall beds. It suggests at once the 

 sugar maple {Acer saccharuni Marshall) of the East and is not greatly 

 unlike small leaves of A. inacropliyllmn Pursh, the common maple of 

 the west coast. 



This species is named in honor of Mr. V. C. Osmont, of the Univer- 

 sity of California, who collected it. 



Locality. — Bridge Creek, Oregon. Collected by Merriam's party 

 in 1900. (Type in Mus. Univ. Cal., No. 2505.) The fragmentary leaf 

 above described is No. 8488 in the U. S. Nat. Mus. It was collected 

 by Condon. 



