﻿PLATE III. 



[Enlarged two and two-thirds times.] 



Fig. 1. Sijnaptomys cooperi. Eoan Mountain, North Carolina. 

 (No. 50865, U. S. Nat. Mus.) 



1. Left mandible from beneath ; bone ciTt away to expose roots of 



teeth . 



la. Left mandible from inner side; bone cut away to expose roots of 

 teeth. 



2. Fhenacomys oramontis Ehoads. Mount Bater, British Columbia. 



(No. 3562, collection of Gerrit S. Miller, jr.) 



2. Left mandible from beueath; bone cut away to expose roots of 



teeth. 



2a. Left mandible from inner side; bone cut away to expose roots of 

 teeth. 



3. Microtas pennsylvanicus. West Tisbury, Mass. 



(No. 1885, collection of Gerrit S. Miller, jr.) 



3. Left mandible from beneath; bone cut away to expose roots of 



teeth. 



3a. Left mandible from inner side ; bone cut away to exi)Ose roots of 

 teeth. 



4. Evotomys gapperi.^ Seekonk, Mass. 



(No. 193, collection of Gerrit S. Miller, jr.) 



Left mandible showing effect of excessive wear on teeth. 



84 



O 



