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POPULAR SCIENCE REVIEW. 
Laurineae and two Aralice ; the former possessing Miocene affinities; the 
latter having “ the same degree of relation to Cretaceous types of Nebraska 
as to Pliocene species of California ; ” and its Miocene affinities are further 
witnessed by the presence of Taxodium distichum miocenicum and of Populus 
arctica. The species common to this and both the higher and lower groups 
are of Miocene type, but Professor Lesquereux says tl This small Flora seems 
to represent a peculiar stage intermediate between the first and the third 
division,” and further on he remarks that 11 according to Professor Cope’s 
statement, bones of Eocene vertebrate animals have been found in con- 
nection with it,” and seems inclined to regard it provisionally as Upper 
Eocene. 
The third group, that of Carbon, is manifestly related to the Miocene both 
of Europe and Greenland, not only by the general facies of its plants, but 
•also by the presence of numerous species such as Platanus ciceroides and 
GuUlelmce, Populus arctica , Taxodium distichum , and species of Acer , Betula , 
Quej'cus, and Corylus. Palms are entirely wanting, not even the doubtful 
fruits ( Palmocarpon ) which occur in the second group being found here. Its 
probable age is Middle Miocene. 
In the fourth, or Green-River group, we have the same predominance of 
unmistakable Miocene forms, but many of its species display still more 
modern relationships, and the author regards it as Upper Miocene. Of course 
the whole of these geological divisions are to be regarded as provisional and 
approximate only ; they are, as the author says, “ like the first outlines traced 
for the preparation of a map : they may be erased or modified ; the spaces 
have to be filled as our acquaintance with the Tertiary becomes more inti- 
mate.” The sequence of events indicated, as Professor Lesquereux thinks, by 
the result of his researches, as also his opinion upon the position in the geo- 
logical series of Lignitic beds, as a whole, may be gathered from the follow- 
ing extract. He says, “I readily admit the facts, established from sufficient 
evidence, that a fossil Cretaceous fauna has left traces of its presence up to 
the very base of the Lower Lignitic measures, and that there the remains of 
a few invertebrate animals and those of one Saurian, all of Cretaceous types, 
have been found in connection with plants whose characters have been con- 
sidered until now in Europe as representing a Tertiary Flora. Is the flora 
to decide the relation of age of the formation, or the Saurian bones of Black 
Buttes, with the few shells of brackish water, either found there, or which 
may be found hereafter in the same circumstances P The slow upheaval of a 
new land at and from the base of the Lignitic is sufficiently evidenced. . . . 
This land, which, rising up, is cut, of course, by shallow brackish swamps or 
estuaries, is the beginning of a whole formation of wide surface and great 
thickness, where the plants, preserving their Tertiary characters, have consti- 
tuted the materials for the composition of the numerous coal strata, which 
constitute an essential part of it. In those brackish estuaries paleontolo- 
gists have already recognized species of positive Tertiary relation, mixed 
with a few remains of Cretaceous types. But these low swamps drying up, 
their Cretaceous fauna is gradually reduced in its representatives by the in- 
fluence of different atmospheric circumstances, while that of younger types 
becomes predominant. Henceforth the Cretaceous animals appropriate to 
deeper water may live still ; their remains may even be found hereafter 
