SCIUEOMORPHA. 82i> 



and superior aspect of the muzzle are regularly convex in ti-ansverse sec- 

 tion. The inferior incisive alveolus is inclosed entirely in the plane of the 

 ramus, and extends posteriorly to below the last molar tooth. The masse- 

 teric ridge is ver}' oblique, and rises to a median point below the second 

 molar. The coronoid process rises from the front of the last molar. 



Measurements. 



M. 



Length of superior molar series 008 



„• . i. , • , < anteroposterior 004 



Diameter of second superior molar ■; ' 



< transverse w6o 



_. , i- X, • 1 1 (anteroposterior 0020 



Diameter of third superior molar.; ' ... 



< transverse uu-jo 



Width of superior incisor 0020 



Length from base of tirst superior molar to base of incisor 0065 



Width between bases of first molars 002O 



Length of first inferior molar 0033 



Depth of ramus at second molar 0050 



Width of ramus below second molar 0035 



This species was evidently abundant during the early Miocene period 

 in Oregon. I have received numerous specimens from the John Day 

 region from Messrs. Sternberg and Wortman. 



Meniscomys liolophus Cope. 



Bulletin U. S. Geol. Survey Terrs., VI, p. 366. 

 Plate LXIII; fig. 11. 



This species is known from a crushed skull, which displays the second, 

 third, and foui-th superior molars and the superior incisor in good preserva- 

 tion. 



The superior molar teeth indicate that this is the largest species of the 

 genus. Their characters place it between the extremes of form represented 

 by the 3L hippodus and the Jf. iiitens. The crowns of the teeth are short, 

 and the roots are long. The external V's are distinctly inflected, and are 

 separated by a deep notch. The external dividing ridge is not prominent, 

 and the posterior V is smaller than the anterior. The internal lobe is a 

 simple raised border, which would be crescentic in section. It sends a ridge 

 inwards to the anterior intermediate tubercle. The intermediate tubercles 

 are low cones, and the posterior is connected with the apex of the posterior 

 V by a low, simple ridge. 



The entire absence of crenations and plications of the crests and lobes 

 of the superior molars distinguishes this species from the M. cavatus and M, 



