WARD,] JURASSIC FLORA OF OREGON. 375 
here, and all the localities were visited, several new ones found, and 
the whole district searchingly explored. Buck Mountain was several 
times climbed, the original locality of Mr. Todd carefully worked, and 
other plant-bearing beds discovered in the Todd Gulch below, and at 
other points both north and south of this. The collections from this 
region were no longer confined to ferns, but included several of the 
other distinctively Jurassic types of vegetation found below. 
The most extensive collections were made in beds of slate overlying 
heavy conglomerates on the above-mentioned stream nearly due north 
of Buck Peak. The Day Hydraulic Gold Mining Company has dammed 
the stream at this point and built a conduit to the mines some distance 
below. The plant-bearing slates commence immediately below the 
dam, and it was in this first or stratigraphically lowest bed that Mr. 
Storrs made his principal previous collections. The beds have a dip 
toward the coast of from 35° to 40° and the strike is from 15° to 20° 
east of north, but in tracing them up the mountain side the strike was 
found to vary considerably. This plant-bearing stratum is only a few 
feet thick, and is overlain by a bed of conglomerate 50 feet or more in 
thickness. Following the bed of the stream down, this is crossed and 
another bed of slate is encountered, similar in general appearance to 
the first. This is also plant-bearing, and yielded by far the larger part 
of the specimens collected. It also preserved them better, and the most 
complete impressions were found here. Although the principal plant- 
yielding strata of the two beds of slate are separated by about 75 feet 
of vertical thickness, no very marked difference in the flora was appar- 
ent. Certain ferns in the lower bed were less common in the upper, 
and the latter yielded a larger proportion of broad-leaved cycadean 
genera, such as Ctenis, Ctenophyllum, and perhaps Pterophyllum. 
The species of Ginkgo, mentioned by Professor Fontaine (supra, p. 378) 
as occurring in Mr. Storrs’s collection, is one of the most abundant 
fossils of this upper horizon, and very fine specimens were obtained. 
It is possible, as he suggests, that more than one species are repre- 
sented, as some specimens have shorter, blunt lobes and others long 
and pointed ones. 
This form, although not found in the Oroville flora, really consti- 
tutes one of the strongest proofs that we have of the Jurassic age of 
the beds. The digitate-leaved Ginkgos are an ancient type and mark 
a special stage in the progress from the Baiera of the Rhetic to the 
only slightly lobed Ginkgo of the late Cretaceous, the Tertiary, and the 
present. It is characteristic of the Brown Jura (Lias or early Oolite) 
of Siberia.. Associated with this form were.found fruits which may 
have been borne by them. 
It may be added that these Ginkgo forms were also found on Buck 
Mountain. Professor Diller and Mr. Brown brought in a specimen 
on the 13th, which they collected in a gulch some distance north of 
