BPICONITINENIAL SEA OF JURASSIC AGE. 263 
This fauna according to Hyatt belongs to the Oxfordian stage 
of the Upper Jura or Malm. In the Taylorville series of Cali- 
fornia he recognized the Callovian, the Oxfordian and the 
Corallian stages of the Upper Jura. Butas has been stated above 
none but the middle stage has been recognized in the Interior. 
Relation of the interior fauna to the northern eurasian fauna.— 
The discovery of beds of Jurassic age in the interior was first 
announced by Meek* in 1858. In correlating these beds with 
the Jura of the Old World he says: ‘‘The organic remains found 
in these series present, both individually and as a group, very 
close affinities to those in the Jurassic epoch in the Old World ; 
so close indeed, that in some instances, after the most careful 
comparisons with figures and descriptions, we. are left in doubt 
whether they should be regarded as distinct species, or as vari- 
ties of well-known European Jurassic forms. Among those so 
closely allied to foreign Jurassic species may be mentioned an 
Ammonite we have described under the name of Ammonites corat- 
formis which we now regard as probably identical with Azmmonites 
cordatus of Sowerby; a Gryphea we have been only able to dis- 
tinguish as a variety from G. calceola Quenstedt; a Pecten, 
scarcely distinguishable from Pecten lens Sowerby ; a Modiola, 
very closely allied to M. cancellata, of Goldfuss; a Belemmnite, 
agreeing very well with Bb. excentricus.” 
Since the publication of the above statements by Meek the 
paleontology of the European Jura has been more completely 
worked out and some of the faunas, particularly that of north- 
ern Russia, are found to have still closer affinities to the Ameri- 
can interior fauna. The Jurassic faunas of America have also 
received many additions at the hands of the American paleon- 
tologists Gabb, Hyatt, Meek, Smith, Stanton, White, Whiteaves, 
and Whitfield. All of these studies have tended to strengthen 
the opinion just expressed. 
The following comparison of forms which are so closely 
allied as to deserve, in many cases, to be called varieties of the 
same species will serve to show the close affinity of the interior 
* Geological Report of the Exploration of the Yellowstone and Missouri Rivers. 
