58 



Measurements of type specimen. 



MM. 



Total height of tooth posteriorly • 28 



Height of crown posteriorly 1" 



Antero-posterior diameter of crown 27 



Anterior transverse diameter of crown 23 



Posterior transverse diameter of crown 18 



Pal^olagus turgidus, Cope. 



A left mandibular ramus from the Cypress hills was referred by Cope, in 1891 (part I, 

 this volume, p. 5, pi. XIV, figs. 9, 9a), to this species. The specimen lacks the upper part 

 of the anterior lobe of P^ and the upper end of the incisor. The posterior molar is missing, 

 but its approximate size is given by its alveolus. The other lower teeth are perfect. 



Comparing the specimen with the rami of this species figured by Cope, in his " Tertiary 

 Vertebrata," 1884, pi. LXVII, it is seen that the space occupied by the molar-premolar series 

 is slightly greater, but the depth of the jaw is the same, as is also the size of the diastema 

 behind the incisor. The teeth appear to have the same relative size to each other, and the 

 internal enamel inflexion, apparently, has a like development. Matthew has placed this 

 specimen, described by Cope in 1891, in his species P. hrachyodon (op. cit., 1903, p. 217) 

 which is of the size of P. turgidus, but differs from it, as the name implies, by being more 

 brachyodont. Other characters ascribed to P. hrachyodon as distinguishing it from P. tur- 

 gidus are P^ smaller and more conical, m^ apparently larger, the internal enamel inflexion 



less persistent. In lower jaw Pj shorter, more conical, and the inflexion disappearing earlier 

 than in P. turgidus. These distinguishing characters are not apparent, to the writer, in the 

 Cypress Hills specimen, which is here left under Cope's name. 



Measurements of Cypress Hills specimen 



MM. 

 Molar-premolar series 18 



Third premolar : 



Antero-posterior diameter 3.4 



Transverse " , 2-4 



Height above alveolar rim 51 



Posterior molar : 



Antero-posterior diameter 2-8 



Transverse " 9 



T ength of diastema behind incisor 11-2 



Depth of ramus beneath Pj , a . g 



Pal^olagus iiAYDBNi, Leidy. 

 Plate YIII, figs. 21-25. 

 Another species of Palceolagus, distinct from the preceding, is represented by teeth from 

 both jaws mcluded in the collection of 1904. These teeth agree in size with those of P. 

 haydem, the type species of the genus (Oligocene (White River) of Nebraska, South Dakota, 

 &c. , established by Leidy in 1856; they are for the present referred to that species. On 

 plate VIII, are figured three of these teeth, an upper premolar, an upper molar, and . 

 lower molar, from which the following measurements are tal^en ;— 



