1882.] 4bd [Cope. 



The Microsyops spierianus differs from this, species in its smaller size 

 (true molars .008) and in the presence of posterior internal cusps of the 

 true molars. 



The Hyopsodus acolytus was found by Mr. D. Baldwin, in New Mexico. 



■ 



Creodojstta. 



Sarcotliraustes antiquus Cope, Proceeds. Amer. Philos. Soc. 1881 (1882), 

 p. 193. 



Dissacus camifex Cope, Amer. Natst. Oct. 1882 (Sept.), p. 834. 



Dissacus navajovius Cope, loc. cit. 1881, p. 1019. Mesonyx navajovius 

 Cope, Proceeds. Amer. Philos. Society, 1881, p. 484. 



Triisodon quivirensis Cope Amer. Nat. 1881, p. 667. 



Tri'isodon heilprinianus Cope, Proceeds. Amer. Philos. Soc. 1881 (1882), 

 p. 193. 



Deltatherium fundaminis Cope, Amer. Nat. 1881, p. 237 ; 1881, p. 337. 

 Lipodectes penetrans, loc. cit. 1881, p. 1019. 



Deltatherium oaldwini Cope. 



This Creodont is known only from a portion of a right mandibular 

 ramus which supports the two last premolars, and the first true molar with 

 part of the second. It differs from the D. fundaminis in its materially 

 smaller size, and in the forms of the teeth. The first true molar is a more 

 robust tooth, and the basis of the posterior or heel crest is more rounded, 

 and less angulate. The anterior inner cusp projects less anteriorly. The 

 fourth premolar has a distinct anterior basal lobe which is wanting in the 

 D. fundaminis. Its heel is short and wide, and the posterior face of the 

 principal cusp is flat, and there is a rudiment of an internal tubercle on its 

 side. The second premolar is elevated and acute, has no anterior basal 

 lobe, and has a very short wide heel, enamel slightly roughened. The 

 animal was rather aged. 



Measurements. M. 



Length of P-m. ii and iii and M. ii I . . . .0160 



Diameters M. i { anteroposterior 0058 



t transverse 0040 



Elevation of crown of P-m. iii 0052 



Depth of mandible at M. i 0180 



From the Puerco beds of N. W. New Mexico. Dedicated to Mr. D. 

 Baldwin, the discoverer of the Mammalian Fauna of the Puerco beds, 

 which is one of the most important in the history of American Palaeon- 

 tology. 



Deltatherium interruption Cope. 



The smallest species of Deltatherium is, like the D. baldicini, only repre- 

 sented by the anterior part of a right mandibular ramus, which supports 

 the last premolar and the first true molar, with the bases of the other pre- 



