1903.] Matthew, Fauna of Titanotherium Beds of Montana. 2 I 7 



in P . haydeni. The internal enamel inflection on the upper 

 teeth is less deeply impressed and less persistent; it has dis- 

 appeared on all the older individuals, as it does in P. iur- 

 gidits, but at an earlier age; in P. haydeni only a few of the 

 very oldest animals have lost this inflection. The last upper 

 molar is larger than in P. haydeni. In the lower jaw P3 has 

 a less persistent external enamel inflection, so that in old 

 individuals it becomes one-lobed, a character seen also in very 

 old individuals of P. tnrgidus, but which I have not seen in 

 any example of P. haydeni. 



Measurements. 



Upper molar-premolar series 12. mm. 



Lower " " 11. 



Post-canine diastema in lower jaw 8. 



Palaeolagus brachyodon, spec, no v. 



PalcEolagus ? tnrgidus, P.? triplex, Douglas, Trans. Am. Phil. Soc. 

 1 90 1, Vol. XX, p. 6. Not of Cope, except: 



Palccolagus turgidus Cope, Geol. Sur. Canada. Contrib. to Can. 

 Palffiont. Vol. Ill (quarto), p. 5, pi. xiv, fig. 9. Not of previous pub- 

 lications. 



This species is of the size of P. tnrgidus, and probably the 

 specimens referred by Mr. Douglas to that species and to P. 

 triplex really belong here. It is more brachyodont than tur- 

 gidus, and much more so than any other species of PalcBola- 

 gus. P^ is smaller and more conical, m3 appears to have been 

 larger, the internal enamel inflection less persistent. In the 

 lower jaw P3 is shorter, more conical, and the inflection dis- 

 appears a little earlier than in P. tnrgidns. 



Twelve specimens of more or less complete upper or lower 

 jaws represent this species in our collection. 



j^Ieasurenients. 



Molar-premolar series, upper jaw (m3 estimated). . 16. mm. 



" " " lower jaw 15. 



P^, longitudinal 1.5 



" transverse 2.5 



