Bibliographical Notices. 



431 



fossils are apparently comparable with those from the Jndith-Eiver 

 beds proper in Moutaua. The Judith-lliver beds of the Laramie 

 group lie above the Fort Pierre and Fox Hills beds ; but the Belly- 

 Kiver vertebrates, judging by the stages of vertebrate evolution, 

 have older characters— that is, they present more primitive features 

 than are found in those of the Laramie and the Fort-Eentou groups. 

 Mr. Osborn's provisional correlation of the formations (at page 9) is 

 as under : — 



Freshwater. j Paskapoo (no ] p^rt Union. 



[ Dinosaurs). j 



Bracliisb and 

 freshwater. 



Edmonton. 



Laramie and \Tncevatops,Torosaimis, 

 Judith Kiver. I f^^^^Zs'""'' 



Marine. 



Fresh and 

 brackish water 



{ Pierre and "I Fox Hills. 



\ Fox-Hills group. J Fort Pierre. 



( Stereocephalus, Mono- 

 U,, -R. r Montana expo- J ^^''"f- C<^^tops, 



1 ^'^^^ ^^^«^- 1 sures in pirt. i ^^^chodon, Dermo- 



\ Compsomys, Ptilodon. 



Sandy clays and | ^^q ^^^^ 

 sandstimes. J 



Niobara. 



Fort Benton. 



Fort Bentuu. 

 Dakota. 



It has yet to be determined -whether or not all the fossils recorded 

 as from the Judith-River beds are from Montana or from the 

 Laramie group. 



The geological succession of the groups according to the Geolo- 

 gical Survey appears to be as follows: — 



Laramie 



00 (Eocene Tertiary). 



\ Edmonton ( Upper Cretaceous). 

 Fort Pierre and Fox Hills. 

 Belly Eiver. 



Niobara and Fort Benton. 

 Dakota (with an Upper Cretaceous flora). 



" The conclusion is that the Belly-River fauna is more ancient 

 in character, both as to the older types of animals which it con- 

 tains and as to the stages of evolution [shown] among animals 

 which are also represented in the Laramie. The geological interval 

 represented by the Fort- Pierre and Fox-Hills marine beds was 

 accompanied by the extinction of certain Jurassic types and pro- 

 gressive evolution of persistent types. Finally, the fossil vertebrates, 

 hitherto described from Montana, probably are, in part at least, of 

 Mid-Cretaceous or Belly-River age " (page 21). 



Details of the fossils are given at pp. 1 6-21 and tables of rela- 

 tionship and distribution at pp. lU-15. 



