674 



SCIENCE. 



[N.S. Vol. XVI. No. 



magnus Leidy. From Moreau River, South 

 Dakota, Leidy has described two plesiosaurs, 

 Nothosaurops occiduus and ' Ischyrosaurus 

 antiquus; whether these animals are of Belly 

 River age or more recent is not known. 



Turtles of the suborder Trionychia are 

 abundant. One species, Trionyx foveatus, is 

 common .to the Judith and Belly River series ; 

 another, T. vagans, to the Belly River and sup- 

 posed ' Ft. Union ' beds. The order Oryptodira 

 is represented in the Cretaceous by large 

 swamp turtles related to the Dermatemydidse, 

 but belonging to the family Adocidse ; these are 

 Adocus lineolatus Cope, A. {Basilemys, or 

 ' royal turtle,' Hay) variolosus and A. (Basil- 

 emys) imbricarius ; the royal turtle is very 

 large and elaborately sculptured. It is im- 

 portant to note that the two species first 

 named are found both in the Belly River and 

 in Montana ( ? ' Ft. Union '), testifying to the 

 Mid-Cretaceous age of the latter. The pres- 

 ence of numerous species of the Jurassic fam- 

 ily Pleurosternidse (order Pleurodira or Am- 

 phichelydia) is another distinctly ancient feat- 

 ure of this fauna; two of these, Compsemys 

 vicius and C. ohscurus Leidy, are described 

 from Montana. A third member of the same 

 family, Baena hatcheri, is noteworthy as the 

 only species of vertebrate thus far recorded 

 which is common to both the Belly River and 

 Laramie. A fourth new species, B. aniiqua, is 

 described from the Belly River. Polythorax 

 missuriensis from Montana is also referred by 

 Hay to the Pleurosternidse. Mr. Lambe pro- 

 poses the new genus and species, Neuranhylus 

 eximius, a new chelydroid turtle, distinguished 

 by a supernumerary costal. 



Belonging to the rhynchocephalia, Champ- 

 sosaurus, according to Cope is represented by 

 five species of the Judith River, one of which, 

 C. annectenSj is also determined in the Belly 

 River. As Cope has identified this genus in 

 the basal Eocene, it is not distinctive as to age. 



The sculptured tooth named Troodon formo- 

 sus by Leidy is common to the Belly River 

 and Judith River beds; it is uncertain 

 whether this is a lizard or a stegosaur, probably 

 the former. Palwoscincus costaius Leidy is 

 also common to the Judith and Belly River 



series. A clearly distinct species is P. asper 

 Lambe from the Belly River. 



The species Grocodilus humilus of the Ju- 

 dith River is provisionally identified by Mr. 

 Lambe in the Belly River. These beds also 

 contain another Montana crocodile, BottosoM- 

 riis perrugosus. Cope. 



Passing to the dinosaurs, as stated above, 

 the presence of Stegosauria is an ancient char- 

 acteristic. From the ' Middle Cretaceous of 

 Wyoming,' Marsh determined the Stegosaur 

 A^odosaurus (' The Dinosaurs of North Amer- 

 ica,' p. 225). Probably allied to this or to 

 the Polacanthus of the English Wealden, is 

 the remarkable new animal, Stereocephalus 

 tutus, in the Belly River series, with solid 

 skull armature and a ring of postcranial, 

 pointed ossicles. 



The carnivorous dinosaurs and the collateral 

 families will probably be greatly elucidated 

 by the separation of the Mid- from the Upper 

 Cretaceous types. Among the former the 

 genera Deinodon and Aublysodon Leidy and 

 Ornithomimus Marsh, all Montana types, de- 

 serve first mention. After Marsh had substi- 

 tuted the name Drypt.osaurus for the preoccu- 

 pied name Lwlaps (which Cope had employed 

 for an Upper Cretaceous of New Jersey carni- 

 vore) it was generally supposed that all large 

 Cretaceous carnivores should be referred to 

 Marsh's genus. If, however, the large Judith 

 River type, which has its counterpart in the 

 Belly River, is older than the true Laramie 

 type, it is in all probability generically distinct 

 and Leidy's name Deinodon should be applied 

 to it.* This name was securely founded on 

 megalosaurian teeth, and those first mentioned 

 in both Leidy's descriptions and first figured 

 in his memoir on the Judith River vertebrates 

 must be regarded as valid types irrespective of 

 the following facts: (1) that Leidy expressed 

 some uncertainty as to his separation of 

 Deinodon from the English Jurassic genus 

 Megalosaurus; (2) that he associated with the 

 types a number of large serrate incisor teeth, 

 truncate posteriorly, which probably belong 

 with Deinodon; (3) also smaller non-serrate 



* Dr. 0. P. Hay {Amer. Geologist, XXIV., 1899, 

 p. 346) is of the opinion that Cope was justified 

 in rejecting the name Deinodon. 



