8 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN 
If these facts and conclusions are considered as a whole, it is prob- 
ably fair to assume, from the evidence which they present, that the 
relative proportions of the two classes of vegetation in the flora were 
about the same as at the present time, but that the gymnosperms 
included a larger number of species than now obtain. 
NIETHODS PURSUED IN THE EXAMINATION OF THE MATERIAL 
Impressions in the Clay Layers.—Nothing special need be described 
in regard to the methods pursued in the examination of the remains 
and impressions obtained from the clay layers, as this material was 
not different from that with which the paleobotanist ordinarily has 
to deal. All of the larger specimens with well defined external 
characters were merely drawn natural size, in order to show the 
general appearance which they present to the unaided eye, and to 
enable comparisons to be made with Cretaceous species elsewhere 
similarly figured. These are included on Plates 3-6. 
Lignitic Material—The material composed of lignitic remains, 
especially such as formed the mass of the finer debris, was found to 
require special preliminary treatment in order to prepare it for crit- 
ical examination, and some account of the methods pursued in its 
treatment and preparation has seemed to us advisable, especially as 
the results attained are almost entirely due to improved technique. 
This material, while it occurs in the form of a concentrated lignitic 
layer, contains a considerable admixture of clay and very fine sand. 
Further, even where the massed debris is almost pure lignite, it is 
so compacted together by pressure and chemical action that it is 
impossible to isolate the fragments satisfactorily by ordinary mechan- 
ical methods. It was ascertained, however, that maceration in 1-3 
per cent. caustic alkali had the double effect of separating the frag- 
ments from the matrix and from each other. | such material was 
therefore subjected to this preliminary treatment. 
After maceration for two or three days in the weakest solution 
of alkali which would effect isolation of the fragments, the disin- 
tegrated material was washed carefully with runnning water, on 
trays made of mosquito-screen wire, during which process, in order 
that the weight of the mass might not break the more delicate isolated 
fragments, the trays were kept immersed almost to their tops. The 
latter precaution was found to be a highly important factor in securing 
