17 



amily PleurosternidcB (order Pi^eurodira or Amphichelydia) is another distiuctively 

 ancient feature of this fauna ; two of these, Compsemi/s victus and C. obscurus, Leidy, are 

 described from Montana. A third member of the same family, BaeJia halcheri, is note- 

 worthy as the only species of vertebrate thus far recorded which is common to both the 

 Belly Eiver and Laramie. A fourth new species, B. antiqua is described from the Belly 

 Kiver. Polythorax missuriensis from Montana is also referred by Hay to the Pleurosterni- 

 dcE. Mr. Lambe proposes the new genus and species NeuranJajlus eximius, a new chelydroid 

 turtle, distinguished by a supernumerary costal. 



Rhynchocephalia. Champsosaurus according to Cope is represented by five species 

 in the Judith River, one of which, C. annectens is also determined in the Belly Eiver. As 

 Cope has identified this genus in the basal Eocene, it is not distinctive as to age. 



Lacertilia or Stegosauria. The sculptured tooth named Troodonformosus by Leidy 

 is common to the Belly Eiver and Judith Eiver beds ; it is uncertain whether this is a 

 lizard or a stegosaur, probably the former. P alceoscincus costatus, Leidy, is also common to 

 the Judith and Belly Eiver series. A clearly distinct species is P. asper, Lambe, from the 

 Belly Eiver. It is important to determine definitely whether these animals are Lacertilia 

 or Stegosauria. 



Another sculptured tooth, Iguanavus teres, is described by Marsh from the Laramie 

 and referred to the Iguanida. The same author has named PaUeoscincus latus from the 

 Laramie, and placed Palceoscincus among the Stegosauria. 



Crocodilia. The species Crocodilux humilus of the Judith Eiver is provisionally 

 identified by Mr. Lambe in the Belly Eiver. These beds also contain another Montana 

 crocodile, Bottosaurus perrugosus, Cope. 



Dinosauria : Stegosauria. As stated above, the presence of Stegosauria is an 

 ancient characteristic. Marsh (op. cit., p. 242) has referred the genus Palmoscincus to this 

 order. From the " Middle Cretaceous of Wyoming ", Marsh detei-mined the Stegosaur 

 Nodosaurus (op. cit., p. 225). 



Probably allied to this is the remarkable animal, Stereoceplialus tutus, discovered by 

 Mr. Lambe in the Belly Eiver series, with solid skull armature and a ring of postcranial 

 pointed ossicles. 



No evidence of Stegosauria, with the possible excex^tion of Palceoscincus, has been 

 recorded from the Wyoming Laramie, Upper Cretaceous. 



Dinosauria : (Theropoda) Megalosauria, family Megalosauridre. The carnivorous 

 dinosaurs and their collateral families will probably be greatly elucidated by the separa- 

 tion of the Mid- from the Upper Cretaceous types. Among the former the genera Deinodon 

 and Aublysodon, Leidy and Ornithomimus, Marsh, all Montana types, deserve first mention. 



After Marsh had substituted the name Dryptosaurus for the preoccupied name 

 Lcelaps (which Cope had employed for an Upper Cretaceous of New Jersey Carnivore) it 

 was generally supposed that all large Cretaceous carnivores should be referred to Marsh's 

 genus. If, however, the large Judith Eiver type, which has its counterpart in the Belly 

 Eiver, is Mid-Cretaceous, it is in all probability generically distinct and Leidy's name 



