59 

 Measurements. 



Upper leib premolar, 1, fourth premolar (plate VIIT, figs. 22 and 23) :— 



Antero-posterior diameter of grinding surface 2 



Transverse diameter of grinding surface 2-8 



Upper right molar, 1 first molar (plate VIII, fig. 21) :— 



Antero-posterior diameter of grinding surface , 2-0 



Transverse diameter of grinding surface 2-6 



Lower right molar (plate VIII, figs. 24 and 25) :— 



Antero-posterior diameter of tooth above 2-3 



Transverse diameter of anterior lobe above 2-2 



It is likely that more than two species of Palceolagus are represented from the Cyyress 

 hills. Among the separate teeth, obtained in 1904, are a number of incisors of rodents, 

 some of which are probably referable to Palceolagus. 



CARNIVORA, 



Ht^nodon crubntus, Leidy. 



. Plate VII, 1, 2 and 3. 

 Hymnodon cruentus, Leidy, 1853. Proc. Acad. N'at. Sci., Phila., vol. VI, p. 392. 



" " Leidy, 1869. The extinct mammalian fauna of Dakota and Nebraska ; 



Jour. Acad. Nat. Sci. Phila., second series, vol. VII, pp. 47 and 369, pi. V, figs. 10, 11. 



The anterior half of a left mandibular ramus is referred to this species, and represents 

 the second member of the Hysenodontidse to be recorded from this locality, the first being 

 Semipsalodon grandis described by Cope. 



This specimen shows the alveoli of the canine, of the four premolars, and of the ■ first 

 molar ; the roots of these teeth, with the exception of those of the canine and first premolar, 

 being preserved. The alveolus of the canine indicates that the tooth was of large size, 

 directed well upward, and oval in transverse section, with its greatest diameter in an antero- 

 posterior direction. The first premolar, as shown by its alveolus, was single rooted, and 

 followed closely behind the canine. The roots of the first and second premolars passed down- 

 ward obliquely backward, those of the third and fourth as obliquely forward. The first molar 

 was of small size, its antero-posterior diameter being about equal to that of the second pre- 

 molar. 



Although the crowns of the teeth are missing in the Cypress Hills specimen, it is appa- 

 rently properly referable to H. cruentus, Leidy, from the Oligocene of South Dakota and 

 Colorado, judging from its size and general proportions, and the relative spaces occupied by 

 the teeth, in comparison with the published figures of Leidy and Scott. 



The anterior end of the specimen, inside the alveolus for the canine, is broken away, 

 and no trace of the alveoli for the incisors is preserved. Following the plane of the 

 symphysis forward, however, it is seen that there could have been little room for the incisors, 

 which must have been crowded. At the symphysis a small piece of bone, belonging to the 

 right ramus, remains attached to the specimen, and, along the line of junction, indicates a 



