Douglass : Vertebrates from Montana Tertiary. 173 



lakes, two inner and two outer, but these are more oblifjuc than in the 

 premolar, inclining outward and forward. 



The one persistent molar as distinguished from two that were often 

 shed in older animals distinguishes this speci- 

 men from M. inonoJon and J/. />(7//e/is/s. /^^^^ 



I-"ound in Flint Creek beds near New Chi- '^^^^^ 



Isolated teeth. No. 732. Fig. 15. 1%"i!m ^*flr 



A tooth, probably an upper premolar, from 



the Flint Creek beds, has the outer enamel Fig. 15. Mylagauhis 



well broken away, so that the structure of the (^°- 732), Flint Creek 



^, , 1 • 1 r,-, 1 1 1 beds. Showing structure 



tooth can be plainly seen. 1 he enamel lakes ^ , ^ r 



^ 01 teeth. 1 wice natural 



which appear on the worn upper surface of ,1^^ «, a premolar tooth; 

 the tooth are the tops of compressed enamel /;, a molar tooth. 

 tubes which are closed at the bottom. 



These tubes are transversely striated. See Fig. 1%, a. A molar 

 tooth. Fig. 15, h, shows the same structure. 



The molar shows eight enamel lakes in four rows. Sanie locality 

 as the preceding. 



CARNIVORA. 



^lurodon ? brachvgnathus sp. nov. 

 No. 752. Fig. 16. 



This is represented by a large part of a mandible and some portions 

 of the upper jaw \vith all the teeth broken. 



As indicated by the remains, the leading characteristics that dis- 

 tinguish this from all other dogs are the following : Face and hori- 

 zontal portion of mandible greatly shortened yet without reduction 

 in size or number of lower teeth. Mandible deep and robust. 

 Especially heavy in region of symphysis. Teeth crowded and 

 P Y and ^ set oblicjuely in the jaw. 



The dental formula in the lower jaw and undoubtedly in the upper 

 is the same as that of the modern dogs (C lupus, etc.). The greater 

 portion of the premaxillaries and small portions of the maxillaries 

 show that for the length of the face the nasal region was broad, the 

 anterior palatine foramina large. Incisors 2 and 3 were large ; the 

 canine medium sized. Pi one-rooted, but not very small. The cor- 

 responding teeth of the lower jaw evidently had similar proportions. 



