10 



2. Fadnal Characters. 



The Belly River or Mid-Cretaceous fauna is distinguished from that of the Upper 

 Jurassic (ComoBeds, Purbeckien) by the entire absence of Sauropodaaudby the presence of 

 Ceratopsia in great variety. It is affiliated vrith that of the Jurassic, and so far as we 

 know separated from Ihat of the Laramie by the presence of highly specialized Stego- 

 sauria or plated dinosaurs,* by numerous turtles of the Jurassic family Pleuroalernidce, 

 aud by numerous large Plesiosaurs. 



Summarizing the table and vrith allowance for the provisional character of many of 

 tlie determinations and of our incomplete faunal list, it appears that the (i) Belly River, 

 (ii) Judith River and other beds erroneously referred to " Fort Union " of Montana, (iii) 

 Laramie of Wyoming and Colorado are related as follows : 



Total number Cominoa to 

 of species Belly River and 

 named. Montana. 



Fishes 8 3 -species 



Batrachia 5 1 " 



Plesiosauria 4 



Testudinata 15 5 " 



Rhynchocephalia . . . 4 



Lacertilia 5 2 " 



Ophidia 1 



Crocodilia 2 2 " 



Megalosauria 17 2 genera. 



? Stegosauria 5 1 genus. 



Iguanodontia 16 1 " 



Ceratopsia 29 1 " 



Common to 

 Judith River 

 and Laramie. 



1 species. 



. 2 genera. 

 .? 1 genus. 

 .? 1 " 



It should be clearly stated that our knowledge is so inaccurate as to rob this compa- 

 rison of much permanent value. 



There is thus very little in common between the Belly River fauna and the Laramie 

 fauna of Wyoming and Colorado so far as described, except the dinosaur Ornilhomimus 

 aud the very persistent chelouian Baena. Most of the dinosaurs will probably be found 

 to be separated generically. 



On the other hand, so far as known, the Montana fauna has much in common with 

 the Belly River, especially among the Testudinata, Iguanodontia and Ceratopsia. 



In the following table, which has been compiled with the aid of Mr. Lambe and 

 Dr. 0. P. Haj', the geological and geographical references are those given by the authors. 

 Leidv's early references to the " lignite of Nebraska" are to territory now included in Dakota 

 and Montana. In the second column are animals specified as in '"Judith River beds" ; in 

 the third those entered as " Fort Union" or Laramie of Montana, largely Judith River no 



* The only published evidence of Stegosauria in the Laramie of Wyoming and Ck>lorado is the tooth of Palaoscincus. 



