28 



The reader is referred to part I of this volume for Professor Cope's description of the 

 type of this species. 



Five separate teeth from Bone coulee may be mentioned here as apparently belonging to 

 Elotherium. They resemble incisors in, form, and may represent more than one species, as 

 four of them are nearly of a size, whilst one is much smaller. Two of the larger specimens 

 are shown in plate III, figures 1, 2, 3 and 4 ; the small one is shown in figures 5 and 6 of 

 the same plate. 



In his memoir on the Cypress Hills fauna Professor Cope alludes to the fewness of the 

 remains of Oreodonitdce in the collection studied by him. The only specimen mentioned by 

 him is a left lower first premolar which was not assigned to any genus. 



In 1904 a few additional separate teeth were obtained by the writer ; these are noticed 

 as under. 



Agriochcerus antiquus, Leidy. 



Plate II, figs. 16 and 17. 



Three imperfect posterior upper molars, one from the left side and two from the right, 

 represent one or more species of Agriochcerus. Comparing these teeth with the posterior 

 molars of Agrioehmrus antiquus, Leidy, from the Oligocene of South Dakota, as described and 

 figured in the "Ancient Fauna of ISTebraska" (Smith. Contr. to Knowledge, 1854, vol. vi) p. 

 24, pi. 1, the same general form of low cusps, pertaining to this genus, and distinguishing it 

 from Oreodon, is observed. Of these molars, one is of about the size of the corresponding 

 tooth of Leidy's figuted types, the other two are slightly larger. 



One of the above specimens (an upper right third molar, imperfect internally) may with 

 little doubt be referred to A. antiquus; its dimensions slightly exceed those given by Leidv 

 for this species. In this specimen the form of the external median buttress (mesostyle), seen also 

 in a molar to be mentioned presently, is low and flattened from without, quite unlike the high 

 antero-posteribrly compressed mesostyle of Oreodon. In the other posterior right molar the 

 agreement in form with the teeth figured by Leidy is close, so far as can be judged ; the 

 ectoloph is missing and a full comparison is not possible. Its breadth is about the same, and 

 the 'shape of the inner cusps is similar. This tooth is also referred to A. antiquus. The third 

 specimen (plate II, fig. 16), the left posterior molar, has a greater proportionate as well as 

 actual transverse diameter, and may represent a species distinct from A. antiquus. 



Besides the three above mentioned specimeus, there is in the collection of 1904 another 

 left upper posterior molar (plate II, fig. 17). The low rounded form of the mesostyle is here 

 well shown. The tooth exceeds in size the corresponding one of A. antiquus, and the pro- 

 portions of the cusps are somewhat dissimilar ; the flatness of the outer slope of the metacone 

 (postero-exterior cusp) is particularly noticeable. In the absence of better material this tooth 

 is provisionally referred to A. antiquus. 



